pmacs/docs/agent-handoff.md

Agent handoff — cross-machine continuity

Last updated: 2026-08-05. The live CI-triage rule in §5 now points at docs/ci-red-signatures.md (PR #215, merged as main @ 12f2970; its Stage 2 hardening is in flight — see docs/active-work.md), which keys on signature rather than test name; the hazards list this file used to carry is retired, and its two unevidenced entries are audit notes there. Previously 2026-08-04, as bottom-panel Stage 3 #213 — the adopter default flip, which COMPLETES ARC 7: omitting display now means the panel, and the workbench's panel half is done on both frontends. Beneath it the post-release accuracy pass #212 and Distribution Stage 1 #211 — released as v1.1.0, the first pmacs release with prebuilt binaries, which makes journey step 1 reachable without cloning the repository — and the CI CRDT coverage lane #209, the first time CI has ever compiled and run the crdt half of the test corpus, closing a gap that left 279 tests (including a REQUIRED CLAUDE.md gate) unexecuted for the project's whole life. Development moved to the laptop in the same session; the docs absorption #208 sits beneath it. Previously 2026-07-29, as bottom-panel Stage 2B-3 — the GPU panel band, compatible protocol-v21 activation, and the negotiated panel_capable flip, completing Arc 7 Stage 2 — opens atop e003b81. Beneath it, bottom-panel Stage 2B-2 (#187) — the daemon panel projection and the epoch machine — lands on 6c9e765, which is the dired Stage 2 framing (#171) atop the resource-op delete guard framing (#186). Those two are framing-only: both are approved documents with no runtime code, and neither has begun implementation. Beneath them, the docs-only coherence listview correction (#189) and landed-state refresh (#185); the canonical landed base beneath those is 7586905. The runtime anchor beneath them is the M4 config-sink race fix (#174) and bottom-panel Stage 2B-1 (#184). #174 is test-only. #184 is the substantive one — the reserved protocol-v21 bottom-panel wire family, dark by construction, with the production handshake deliberately still advertising v20 — following the Journey/GPU directory-target ratchet (#183), following Journey Stage 1a (#182), which made directory startup one coherent local/daemon/GPU path and incorporated the terminal configuration + copy mode landed-doc work (#180); following terminal copy mode (#178) — C-c C-t materializes a terminal's whole retained range into an ordinary buffer, plus Buffer::set_generated_contents, the first genuinely immutable generated-buffer write path — and its landed-doc pair (#168); following Lean 4 Stage 4a (#179) — the typed-edit consumer chain — and bottom-panel Stage 2A (#177), the classified census routing that makes every Projection-class consumer ask primary_document_window; the bottom-panel Stage 2 framing (#175), terminal configuration Stage 1 (#173) — profiles, scrollback, a per-terminal configurable escape key, and the C-c t opening binding — Lean 4 stages 3a and 3b (#167, #170), pmacs' first Lean language server; the GPU terminal input fix (#166), the double terminal-layout sync that made a GPU terminal untypable; the CRDT undo repro (#157), the inline-math landed-doc refresh (#172), the inline-math slice (#158), the first mathematical typesetting in pmacs; dired Stage 1 (#165), Lean 4 Stage 2 (#161), the dired framing pair (#163/#164), find-file (#162) — the dired arc's Stage 0 — COHERENCE.md (#163), Lean 4 Stage 1 (#160), the minimap blank-slab fix (#159), bottom-panel Stage 1 (#155), the inline-math re-scout (#154), the vterm PTY-flake fix (#153), and the GPU initial-target doc refresh (#152); and before that GPU initial-target (#148, protocol v20), following folding Stage 2 (#149) and its landed-doc refresh (#150), web grammars HTML+CSS (#146), the LaTeX Stage 1 / inline-math framing pair (#144/#145), folding Stage 1 (#142), one-command GPU invocation (#141), the documentation refresh (#140), Vterm Stage 3 (#135), tab-width rendering parity (#137), locals-query processing (#134), modeline detection (#132), mode system wiring (#129), config registry (#127), Vterm Stages 1–2 (#126/#130), and completed Themes Arc 4 (#120/#124/#125). This file is the bridge between development machines. If you are an agent reading this on a fresh clone: this document plus the docs/*-framing.md files ARE your memory. Read this fully before taking on work, seed your persistent memory from it, and update this file (and commit it) whenever project state changes materially — the next machine reads it the way you just did.

For volatile branches, checkpoints, verification, and recovery commands, read docs/active-work.md immediately after this file.

1. Where the project stands (2026-08-01)

• main @ f186253. Bottom-panel Stage 3 #213 completes Arc 7, atop the post-release accuracy pass #212 and 000b6cd / v1.1.0. Beneath that, Distribution Stage 1 #211 lands atop the docs absorption #210, the CI CRDT coverage lane #209, the absorption #208 and cfc1710. Beneath that, nine PRs landed in this order: the ledger absorption #199, the process-signal diagnostic #200, the test ambient-root isolation framing #201, the reap-ledger diagnostic #202, Journey Stage 1b-1 #203, 1b-2 #204 and 1b-3 #205, the ambient-root isolation implementation #206, and discovery Stage 1 #207. Each has its own bullet below; this line is the head-of-main anchor and nothing else.
• Bottom panel Arc 7 COMPLETE — Stage 3 (#213), the adopter default flip. Omitting display now means the panel for listview, compile and terminal; dired keeps "current" because pmacs.path.directory_handler calls it with no display and a flipped default would open pmacs . in a bottom panel. Four hand-written copies of the validator collapsed into one resolve_adopter_display(operation, raw, default) — the default is a parameter, which is what makes dired's exemption visible at its call site instead of hidden in a divergent copy. Durable facts:
  • A visit FROM a panel must never use the raw switch. pmacs.window.switch_buffer replaces the buffer in the ACTIVE window, so from a panel it clobbers the panel itself. The outline's on_visit still did this; the references panel had been migrated to display_file when the arc landed and the outline was missed, because nothing exercised it from a panel until the default flipped. Q#BP11c is the contract: after RET, M-, must FOCUS the still-present panel, not clone its buffer into the document — and an assertion on the active buffer name alone cannot tell those apart.
  • An opt-out that does not survive replay is not an opt-out. compile._last stored {cmdline, cwd} only, so g re-resolved display and silently reverted an explicit "current" to the new default. Anything that replays a stored invocation must store the escape hatch with it.
  • Compile's chords are PANEL-LOCAL, deliberately. All are bound scope = "buffer", so with select = false none dispatch from the document — C-c C-k included. M-x compile.kill still works anywhere via its or compile_slot() fallback. A global chord is a command-surface decision, framed separately.
  • Two q mechanisms coexist by design: presentation history chains in the side slot (C → B → A → delete, Q#BP2c), while p.prev prevents raw-switch and capability-fallback listview loops. Neither supersedes the other.
  • A capability fallback must strip the QUIT ACTION too, not just the side parameters — a quit action stranded on a document window makes a later q try to restore a presentation that never happened.
• The tree primitive ships — listview gained depth, collapse and identity (P5, §14's last missing workbench primitive; implemented, PR held). Rows carry optional depth and id; absent, a row behaves exactly as before, which is what leaves the flat consumers untouched. The LSP outline is the one adopter. Durable facts:
  • Folding is local projection state, not a refresh protocol. Collapse only hides rows and never changes a surviving row's depth, and consumers emit parents before children, so descendants are a contiguous run. The primitive therefore re-renders from its own array without calling the consumer — which is the only reason the anchor consumer works, because the outline has no on_refresh at all. A design requiring the consumer to re-supply rows on every fold would have fitted no existing consumer.
  • Identity is consumer-supplied and compared by equality; the primitive never derives one. item is opaque by design. The outline uses line:col, because the :: parent chain collides on overloads and same-named siblings — exactly where a stale expansion would reattach to the wrong node. Selection is re-seated by id, not by line, since a fold inserts or removes rows above the cursor.
  • has_children must read the FULL row array, not the rendered subset. A collapsed node's children are absent from the rendered map by construction, so asking the view would answer "no" for every collapsed node and make expanding impossible — a self-sealing bug that looks like fold working and unfold silently not.
  • A bite that passes validates the pair, not the test. The first byte-identity injection used row.depth or 0; flat rows have no depth, so it changed nothing and the test "passed" against a regression the flat path is immune to. Ask which defect you injected before believing a green bite.
• pmacs is installable without cloning — Distribution Stage 1, #211, released as v1.1.0. A v* tag builds pmacs and pmacs-gpu on pinned ubuntu-22.04 / macos-15 and publishes a GitHub Release with SHA256SUMS. Journey step 1 works for the first time, and COHERENCE.md §17 moves missing → Partial. Scope was deliberately binaries-only; channels, update, rollback and signing are stated non-goals. Five durable facts:
  • A release build can produce FIVE binaries and three must never ship. Cargo auto-discovers src/bin/*.rs, so pmacs-audit, pmacs_fake_lsp and pmacs_fake_mcp appear alongside the two real ones. Exclusion is two-layered — explicit --bin targets and an explicit staged asset list — and layer 2 is not belt-and-braces: building the branch, target/release still held all three from an earlier cargo test --release, and Swatinem/rust-cache restores exactly that in CI. Archiving target/release would have published a fake language server.
  • env!("CARGO_PKG_VERSION") expands in the crate being COMPILED. InstanceIdentity::for_running_process lived in pmacs-protocol and read it there, so the daemon reported the protocol crate's version to every frontend under a field named pmacs_version. Three tests asserted the right thing and could not fail while both crates read 1.0.0 — diverging them is what made the tests discriminating. A test can be correct and still prove nothing when the two things it compares are equal for an unrelated reason.
  • Pin release runners, never -latest. ubuntu-latest (glibc 2.39) silently produces binaries that fail to load on Ubuntu 22.04 and Debian 12; macos-latest drifts the minimum supported macOS with no commit to point at. And a pinned runner proves nothing about the artifact — the glibc floor is asserted by reading versioned symbols out of the binary (objdump -T | grep GLIBC_), so a bad runner change fails in CI instead of shipping.
  • A tag pushed before its workflow is on the default branch does nothing, silently. on: push: tags resolves the workflow file at the tagged commit, and GitHub registers workflows from the default branch. No run, no error — indistinguishable from "not started yet", which is the worst possible shape for a release step. Confirm a run actually appeared.
  • Verify a release from the DOWNLOADED artifact, and use a negative control. Checking CRDT presence by counting loro strings means nothing without building a non-CRDT binary and getting zero.
• CI runs the CRDT half of the corpus for the first time — #209. .github/workflows/ci.yml had never enabled the crdt feature, so every #[cfg(feature = "crdt")] test was not compiled — not skipped, not filtered, not reported. 279 tests had never executed in CI, 186 of them in the library, behind the cargo test --lib --features crdt invocation CLAUDE.md lists as a required pre-PR gate: a required gate CI had never run. Test (crdt) now runs 3,766 tests, M10 Perf Gates (crdt) covers two suites no workflow had named, and clippy --features crdt is enforced. 275 of 279 recovered; the other four are excluded with stated reasons. Five durable facts, each of which contradicted something previously recorded:
  • gpu-render runs a DIFFERENT PACKAGE (cargo test -p pmacs-gpu) from the root-package GPU suites. The long-recorded fix shape — "move the GPU-requiring crdt suites onto gpu-render, it already has lavapipe" — does not work as written. One job covers the whole corpus instead, which also cannot develop the hole splitting invites: a suite added later would otherwise land in the job needing no GPU and skip there forever.
  • PMACS_REQUIRE_GPU is not uniform. Present in vterm_stage3_acceptance (×2) and bottom_panel_stage2b_gpu_ acceptance (×1), absent entirely from gpu_invocation_ acceptance and gpu_initial_target_acceptance. It cannot serve as blanket proof the GPU suites ran.
  • m10_10_perf is a CI-default regression tripwire, not a bench. Its header says its bounds are "generous … to catch catastrophic regressions, not to verify a tight perf claim", so the absence of #[ignore] is the design. Giving it a perf job would have shipped a coverage reduction inside a coverage lane. Classifying the three _perf suites by filename and marker counts got the one whose name disagreed with its purpose exactly backwards.
  • --keep-going is what turns a clippy run into an inventory. Clippy abandons remaining targets at the first failure, so any un---keep-going list is a lower bound. The recorded seven-item list was stale in both directions: one finding had been fixed incidentally, one was new, and every line number had moved.
  • A feature can matter to a crate a per-test census scores as unaffected. pmacs-protocol's crdt feature gates no tests — 17 either way — but changes cfg!(feature = "crdt") expressions inside the capability defaults, so the same tests exercise different runtime values. Worse, the crate's only use of those defaults was a transport round-trip, which is invariant to the values: an all-false default passes identically. Running code is not testing it, and that gap survived the first review round.
• Two arcs completed in that run, and their lanes are gone from docs/active-work.md accordingly (rule 4 removes a lane once its arc is done and its facts are here): Journey Stage 1 — 1a plus the whole 1b split — and test ambient-root isolation. Discovery and reap-ledger merged a stage each and keep rewritten lanes.

1a. Outstanding work — the whole board, 2026-08-01

Read this before picking anything up. It is the only place the remaining work is enumerated in one view; the per-arc bullets below give the detail. Nothing here is in flight: zero PRs are open at this anchor, so every item is startable.

Arc state, against COHERENCE.md §20's priority order

P	Arc	State	What is next
1	Journey	Stage 1 COMPLETE (1a #182/#183; 1b-1 #203, 1b-2 #204, 1b-3 #205)	Journey runs to step 10. The thin end is now steps 1 (install — that is P8), 11 (background work: visible but no ownership model, §9) and 12 (session restore: desktop-save is opt-in and a documented no-op under a daemon)
2	Workspace + location	Missing; model gap	The long-lead arc. Start before a fifth subsystem grows its own root convention — four have already diverged (§7)
3	Extension ownership	Missing; prerequisite-shaped	pmacs.hook.remove does not exist. That one bug-sized gap blocks §13's disable/uninstall, §10's trust classes, and package-scoped cancellation
4	Discovery	Stage 1 MERGED (#207)	Stage 2 candidates, in rough dependency order: richer M-x rows (protocol change — MinibufferPrompt.candidates is Vec<String>; CompletionPopupRow already proves the pattern), Command gaining title/category/aliases/flags/arg-schema (~147 definition sites), predicate evaluation, help-layer unification, and the help-prefix decision
5	Workbench convergence	Partial; Arc 7 COMPLETE (#213) and the tree primitive is implemented (PR held)	The bottom panel is finished on both frontends and the adopter default is flipped. The tree primitive has landed on a held PR: §14's Tree moves ✗ → ◐ with the LSP outline as its one adopter. Next: adoption — dired's i, then DAP's variables view, which is why it was built first
6	Config productization	Foundation only	Value provenance, then layering, then adoption migration (table-valued settings are the hard prerequisite — ConfigValue is four scalars)
7	Package lifecycle	Not started	Correctly sequenced after P3
8	Distribution	Stage 1 SHIPPED (v1.1.0, #211)	Binaries on tag, checksums, machine-checked glibc floor. Journey step 1 now works and the "invisible until this exists" blocker is lifted. Next is a decision about channels / update / signing, not a queued plan

Open lanes (branch exists, work not finished)

• CRDT half of the corpus is dark in CI — FIXED, merged as #209. Now a lane kept only for three follow-ons (macOS leg, the --lib --features crdt flake, the crdt_replica serde divergence). See the arc bullet in §1. Re-measure before quoting a number, and there is now a tool: scripts/feature-census luajit luajit,crdt. Measured 279 dark at 4223dd3; 275 recovered, 4 excluded with stated reasons. Two corrections it forced are worth carrying: m10_10_perf is a CI-default regression tripwire, not a bench (its bounds are deliberately generous, so #[ignore]ing it to give it a perf job would reduce coverage), and gpu-render runs a different package (pmacs-gpu) from the root-package GPU suites, so the long-recorded "move them onto gpu-render" fix-shape does not work as written.
• Generated-buffer immutability — Stage 1 merged (#191); Stage 2 not started. Four writer mechanisms have still not adopted set_generated_contents; key the inventory by writer, not buffer.
• Bottom panel — Stage 2 complete; Stage 3 is the adopter default flip.
• Folding — Stages 1–2 merged; Stage 3 (GPU) next, with mirror-clear-on-snapshot a named obligation.
• Reap-ledger — diagnostic merged (#202); every disposition change is still parked (below).
• Kill-ring browser + persistence — parked by choice.

Deferred work, by the framing that parked it

Each was a deliberate decision with a stated reason; none is a to-do someone forgot.

• From LSP guidance (#204): build pmacs.error (fifteen guarded call sites reporting through a channel that does not exist); promote the spawn-failure record into Rust's status model so *lsp* shows failures natively; surface LspEventKind::Crashed — a server that started then died is unsurfaced and is a different message.
• From the welcome (#205): the help prefix — C-h is not free; it deletes a word because non-kitty terminals cannot disambiguate Ctrl+Backspace from Ctrl+H (both byte 0x08), so rebinding breaks Ctrl+Backspace on every legacy terminal. Also: make show_help_text adopt the generated-buffer write invariant; onboarding proper (§18's ten-step sequence).
• From discovery (#207): everything in the P4 row above, plus settings value provenance (§11) and closed-set acceptance semantics — completion today is assistance, not validation: resolve_accepted_value returns the literal typed text when no candidate is selected, so a typo still reaches the handler.
• From the reap ledger (#202): Q#RL1's strict-ESRCH probe and Q#RL2's retry policy — neither can move alone, because shutdown()'s loop exits when the ledger empties, so a strict probe without a loop change converts a silent early exit into a guaranteed 2 s stall at every editor exit. Also parked: retargeting to the measured pgid, signal_target's read-then-kill of tcgetpgrp (the "most likely real fix site"), and why a group-directed kill returns EPERM against a live owned child — still unknown.
• From ambient isolation (#206): production still resolves ambient roots by default (only construction gained a parameter); nothing audits what previously wrote into ~/.local/share/pmacs.

Side quests and standing hazards

• pmacs.error is undefined in production. Fifteen if pmacs.error then guards make the silence look deliberate. Report through pmacs.editor.set_status until the channel is built.

• Judging a red CI run: docs/ci-red-signatures.md is the authority. It keys on signature, not test name — a failure in a listed test that lacks that row's fragments is a NEW incident, not a known one. The old rule here ("rerun before concluding") is retired: a green rerun establishes intermittence only, never environmental cause or harmlessness; the same signature again is a second occurrence and stays blocking. One row is an unresolved possible product defect that no rerun can clear.

  This list previously named three tests. The audit found one of them had produced two distinct signatures with different causes, and that two of the four incidents actually seen were absent from it — which is why name-keyed lists are not trustworthy.

• basedpyright hangs forever — always cargo test --test m4_acceptance -- --skip basedpyright.

• The crdt sweep needs cargo build --workspace first, or twelve gpu_invocation_acceptance tests fail on a missing pmacs-gpu binary. cargo build --workspace --no-default-features --features luajit,crdt is the invocation that produces both binaries.

• A shared CARGO_TARGET_DIR makes concurrent sweeps unattributable. Every worktree on this machine resolves to the same target directory, so target/debug/pmacs is a shared mutable file: a cargo test --workspace at default features in one worktree overwrites the binary a running crdt sweep is spawning, and every real-daemon suite then starts the wrong one. Established once, on 2026-08-05, in the Stage 2 hardening sweep — seven failures across three real-daemon suites against a clean baseline, the failure text naming its own cause ("start the daemon built with the crdt feature"), pgrep confirming the rival build, and a re-run from the same tree with a dedicated CARGO_TARGET_DIR giving 41/41. The reciprocal case was seen from the other side the same day. Give a second worktree its own target dir, check for live worktrees before believing a sweep failure, and treat any red from a sweep that overlapped another build as unattributable rather than as evidence. (This mechanism does NOT retroactively explain the tree lane's unclassified occurrence — that one's signatures were destroyed before being read, so it has no captured text to match against this one's, and it keeps two non-causal hypotheses. A mechanism established in one occurrence is not evidence about a different occurrence that was never characterized.)

• A local sweep leaks daemons, and they accumulate across days. gpu_invocation_acceptance's one-command tests leave ~3 orphaned pmacs --daemon processes per sweep, reparented to systemd with deleted sockets; 42 were resident at one point, the oldest four days old. They are a rival explanation for any load-sensitive local failure, so check pgrep -f "pmacs --daemon" before trusting a local red. Lane recorded in docs/active-work.md.

• A local sweep is blind to whichever feature configuration it does not build. Stage 3's census and every verification sweep ran --features luajit WITHOUT crdt, so no crdt-gated suite was exercised and compile_mode_crdt_acceptance reached CI broken. Sweep BOTH configurations before claiming a corpus is green — the crdt job exists precisely because that blindness is easy.

• "My change made this fragile" is a different finding from "this was always flaky", and only one of them is yours to fix. Stage 3 saw two CI runs on one commit fail DIFFERENT PTY/GPU suites — the load-sensitivity signature, on suites the flake list already names. The tell that it was neither: the failures kept landing on GPU terminal tests, and terminal placement was what the PR changed. Those fixtures opened with no display, so the flip shrank the very window whose rendered frames they assert against. Ask which tests and why those, before reaching for a rerun.

• Never hand-roll the dark-test census — use scripts/feature-census. libtest prints name: test with no space before the colon, so a filter written / : test$/ matches nothing and reports a clean zero; a target with zero tests prints its Running line and nothing else, so counting only test lines drops it from the diff; and both configurations need an --ignored pass, or pre-existing ignores get attributed to the feature. Each of those was hit while writing the script, and the second one survived two revisions of a framing doc.

• A green a37 means nothing on its own — the vterm real-daemon acceptance returns ok without running unless pmacs-gpu is built.

• Previous anchor, retained for provenance: 4cd4a7b (the generated-buffer immutability framing #188, the resource-op delete-guard implementation #190, silent-skip arming #192/#193/#194, CI timeouts and concurrency #195, the process teardown stdin-deadlock fix #197, dired Stage 2a #196, generated-buffer immutability Stage 1 #191, and bottom-panel Stage 2B-3 #198).

• Previous anchor, retained for provenance: 6c9e765 (the dired Stage 2 framing #171 and the resource-op delete guard framing #186 — both framing-only, no runtime code, no implementation started — atop the docs-only coherence listview correction #189, atop the docs-only landed-state refresh #185, the M4 config-sink race fix #174 — test-only — atop bottom-panel Stage 2B-1 #184, the Journey/GPU directory-target ratchet #183, Journey Stage 1a #182, incorporating terminal configuration + copy mode landed docs #180, Lean 4 Stage 4b #181, the dired Stage 1 landed docs #169 and the PTY-terminate diagnostic #176, terminal copy mode #178, the GPU-terminal-input landed docs #168, Lean 4 Stage 4a #179, bottom-panel Stage 2A #177, the bottom-panel Stage 2 framing #175, terminal configuration Stage 1 #173, Lean 4 Stage 3b #170, Stage 3a #167, the CRDT undo repro #157, the inline-math landed-doc refresh #172, the bottom-panel landed-doc refresh #156, the inline-math slice #158, dired Stage 1 #165, the GPU terminal input fix #166, Lean 4 Stage 2 #161, the dired framing #164, COHERENCE.md #163, find-file #162, Lean 4 Stage 1 #160, minimap blank-slab #159, bottom-panel Stage 1 #155). Protocol schema support is v6..=v21, the production server-first Hello advertises v20, and a current session nevertheless negotiates v21. All three are true at once, and Stage 2B-3 is what made them compatible: the advertised version is a permanent baseline and the session's real version is settled one message later by the frontend's AttachRequest counter-offer. The bullets below describe the arcs in their own terms; this line is the head-of-main anchor.

• COHERENCE.md is now required reading and a required framing input — #163. It carries the product-coherence thesis, an audited scorecard, per-concern gaps, and §20's priority order, and it is the standard new work is evaluated against. Per CLAUDE.md, every new framing doc must state its coherence impact — journey steps touched, interaction islands added, config-registry adoption, background-work attribution. Its §2 grades the golden journey; Journey Stage 1a moved that grade off "broken at step 3" — see the arc bullet below.

• Journey arc (P1) — Stage 1b-1 LANDED (#203) (docs/journey-stage1b1-compile-defaults-framing.md). Journey step 9 moves Partial → Works: C-c c runs compile.run, and the first prompt is prefilled from the detected project kind via pmacs.compile.defaults (seeded rust = "cargo build", extensible from init.lua). Lua, tests and docs; no Rust change, no protocol change. The ratchet now carries steps 2, 3, 5 and 9.

  • Sharing a resolver is not capturing one. pmacs.minibuffer.read is asynchronous and nothing freezes the active window while a prompt is open, so having the prompt and compile.run call the same cwd resolver still let them disagree: the user could be offered cargo build for A and given a run in B by clicking away mid-prompt. The interactive command captures pmacs.compile.context() once and passes its cwd through to the run. This is Stage 1a's commit_to lesson on a smaller seam — capture at request time, never re-derive when the async work lands. Review found it; the first framing had the weaker design and said it was sufficient.
  • A pin that never crosses the accept boundary cannot see that class of bug. Every originally-proposed pin compared values the prompt and the resolver already agreed on, so the defect above passed all of them. Two pins now accept the prompt and observe a real process.
  • ProjectKind::Cargo does not exist — COHERENCE.md named it twice, citing src/project.rs:77, which is the doc comment; the variant on line 78 is ProjectKind::Rust. Lua never sees the variant anyway: pmacs.project.detect returns the tag string "rust". Corrected in both COHERENCE sites and recorded in its §24.
  • The compile fallback cwd is the process cwd, which under cargo test is the pmacs repo — itself a Cargo project. Any pin asserting the absence of a Cargo suggestion that reaches the fallback reports pmacs's own Cargo.toml. Bite D confirmed it: with the kind derived from the process cwd, the plain-fixture prefill pin still passed and only the nested-project pin caught it. set_search_boundary is no defence — it clamps only a walk starting below the boundary.
  • Named limitation, deliberately unfixed: after pmacs <dir> the active buffer is dired's and pathless (pmacs.buffer.create assigns no path; dired compensates through its own module-local handle_for_buffer), so the cwd falls through to the process cwd. Launched from elsewhere that is the wrong directory. The fix is §8's execution-location model, not a reach into dired's private table. What is guaranteed is that the failure stays coherent: the suggestion always describes the directory the run will use.

• Journey arc (P1) — Stage 1a LANDED (docs/journey-stage1a-framing.md). pmacs . opens a directory instead of exiting 1, on one path: resolve_target_buffer gained a ResolvedTarget::Directory arm ahead of the load, EditorState::open became a caller of it rather than a parallel implementation, and the daemon/GPU bootstrap shares the same arm. Which surface handles a directory is the path.open-directory chain with dired as a replaceable fallback slot. tests/journey_acceptance.rs is the new cross-subsystem ratchet (steps 2, 3, 5 seeded; stages add rows, none removes them). No protocol change.

  • A hook a builtin subscribes to can never be first-claimant-wins for users. HookRegistry::add only appends and builtins load before init.lua, so a dired subscription would always claim before any user listener. That is why dired is a slot (pmacs.path.directory_handler) and not a subscriber — and why clearing the slot has to leave startup succeeding with a status, not exiting 1.
  • A raise and a false are indistinguishable in proceed. run_short_circuit returns proceed = false for both; only HookOutcome.errors separates them, and it decides whether to report, not whether to fall back. Getting this backwards produces a fallback that runs after a user's resolver crashed mid-handling.
  • The listing is async; the bootstrap is synchronous. The whole post-await commit therefore runs against a destination captured at request time (pmacs.window.commit_to), which preflights every precondition before invoking the callback — dired mutates handle state, prev, and paint long before it reaches anything that could refuse, so validating at display time is four mutations too late. Awaiting inside a commit is refused: a yield would restore the scope while the coroutine is still parked.
  • The scope swaps core.active_frontend, not just an override — pmacs.window.buffer()'s no-arg arm reads the ambient active buffer directly, so dired's prev capture would otherwise follow whatever frontend happened to be dispatching. The override also exists, and is load-bearing in exactly one case: a commit reached from inside an interactive command, where the origin would otherwise outrank the ambient value. Bite-testing found N4 green without it.
  • replace_active_buffer does not drop the startup scratch buffer, despite its doc comment having claimed so for as long as it has existed. Its body is one switch_active_buffer call. The comment is corrected here; changing the lifetime is separate work.
  • Stage 1b is the named remainder: compile binding + Cargo defaults, LSP spawn guidance, welcome buffer.

• Terminal configuration + copy mode arc — COMPLETE (docs/terminal-config-and-copy-mode-framing.md rev 4; Stage 1 #173, Stage 2 #178; no protocol change in either, still v20). Stage 1 ships profiles, scrollback, a per-terminal configurable escape key and the C-c t opener; Stage 2 ships copy mode — M-x terminal.copy-mode / C-c C-t.

  • The snapshot MATERIALIZES into an ordinary buffer. That is the arc's organizing decision: isearch, motion, selection and the kill ring work with no new substrate, and "keys must not reach the child" dissolves structurally, because the transport arm keys on is_terminal(buffer_id) and a snapshot is not a terminal. The dispatch-shadow count therefore stays at six.
  • prune reacts to buffer removal rather than causing it — it filters on !registry.contains(buffer_id), so a child exiting does not remove the terminal buffer. That is what makes on_removed a sound teardown hook, and why a finished command's output stays readable.
  • Ownership means "in our own handle table", never found-by-name (dired's F7 rule, re-learned here): snapshot writes use bypass_intercept, so adopting a same-named foreign buffer clobbers user data. Snapshot identity is keyed by comparing buffer handles in an array — BufferIdLua implements __eq but each wrapper is a distinct table key, so comparison works and hashing does not.
  • Profiles are a raw Lua table, joining pmacs.lsp.config and pmacs.pair.sets, because ConfigValue is four scalars with no table kind. The two open-time settings resolve through the global chain (they are read before the identity buffer exists); only terminal.escape-key resolves per buffer, and its cache lives on TerminalSession so its lifetime is the terminal's — value_epoch alone is not a sufficient key, because it does not advance when focus moves between terminals holding different buffer-local values.
  • Criterion 17 is deliberately unpinned, and its bite is now stated correctly. A real semantic frontend proving neither copy is mutated needs the actual GPU binary (the optimistic apply exists only in pmacs-gpu/src/main.rs; the headless SemanticClient has no optimistic path), i.e. the a37 footing §5 warns about. After set_generated_contents the eventual test must look for unauthorized mirror mutation plus daemon refusal — divergence, not the "mutates both sides silently" the criterion originally specified, which can no longer happen and would pass for the wrong reason. A fix can invalidate a test that was never written.
  • Test instruments worth reusing: cat -v is the echo probe, because the screen rejects C0 controls before they reach cells so a raw echoed Ctrl-X is invisible; and such probes must count occurrences rather than test presence, because a single-character probe collides with the child's own banner text.

• PTY terminate diagnostic LANDED — #176 (merge bf8878f, 2026-07-26, one review round; docs/process-signal-tolerance-framing.md rev 4, after three framing rounds). Diagnostic only — no disposition changed. Every call that failed before still fails, with no state transition and no reap-ledger arming; src/process.rs is the only source file touched. It exists because the terminate EPERM flake is real and nothing yet knows why.

  • Why three tolerance rules were all rejected: each concluded something about a process from something that was not about that process. Rev 1 reasoned from an errno alone (EPERM means the caller lacks permission, not that the id was recycled); rev 2 from try_wait, which observes the spawned leader while a PTY signal targets -tcgetpgrp(...) — entities that diverge exactly when job control has moved the terminal; rev 3 from group-directed ESRCH, which proves only that the selected foreground group vanished. This is the reusable shape, not a Unix trivium.
  • Two facts that killed the original argument. group = true is rejected for PTY mode at spawn, so the reap ledger never applies to the PTY path at all; and the ledger's own comment saying EPERM "cannot happen for our own children" drops the entry for bounded growth, not as a ruling that EPERM means dead. A comment stating a belief is not the same as code enforcing it.
  • What ships: a failing kill now reports five separate facts — target source, target kind/value, spawn-time group, errno, and the leader's real try_wait state. The test seam injects the kill result only, never the observation, so the real ChildHandle::try_wait runs against the real child.
  • It is not "strictly additive". try_wait reaps and caches, so an exited child may be reaped earlier than before. That is safe only because portable-pty 0.9.0 returns a std::process::Child on Unix and delegates try_wait to it, so poll_one still sees the cached status — pinned by an exactly-one-terminal-event test rather than assumed.
  • Still open, and still the most likely real fix site: signal_target's read-then-kill of tcgetpgrp. All tolerance rules remain parked pending the evidence this diagnostic produces, as does terminate idempotence for an already-reaped process (a different failure, so a different PR).
  • The diagnostic fired, and what it showed. macOS CI, PR #191, run 30553376486: target=-8619 via group, leader_pid=8619, expected_group=-8619, leader=live — the spec.group pipe path, not the PTY path, with the leader observed alive by a real try_wait. A rerun of the identical head passed 12/12, so it is intermittent.
  • Owning the child does not license dismissing a group error, and the occurrence does not prove the child received EPERM. The failed target was the group -8619; try_wait observed the process 8619. Nothing measured getpgid(8619), so the two are not known to refer to the same thing. What is settled is narrower and still enough: a group target computed from the spawn-time pgid == pid assumption returned EPERM while the leader was alive, which retires "EPERM cannot happen for our own children" as a reason to discard an arbitrary group-directed error. Attributing the errno to the child would repeat the exact error that killed three tolerance rules — concluding something about one entity from something about another.
  • A field named like an observation can be a restatement of its input. expected_group is -leader_pid, and on the spawn-group path the target is -leader_pid too, so the report printed the same number three times and their agreement was arithmetic. Stage B adds a measured_group from getpgid, which is the only field able to disagree — and it still establishes no identity, because it is read inside the same read-then-act window and no portable mechanism closes that for a group (pidfd covers a process; macOS has neither).

• Discovery arc (P4) — Stage 1 LANDED (#207) (docs/discovery-stage1-command-family-framing.md, rev 6, three review rounds). Eleven help.* commands over the existing registries, indexed by M-x help. §5 moves substrate-without-surface → Partial. No Rust: the data was all reachable from Lua, and the settings completion source is a Lua function through CompletionSource::Custom — correcting a default.lua comment that claimed source was a fixed Rust-side vocabulary.

  • Completion is assistance, not validation. resolve_accepted_value returns the literal typed text whenever no candidate is selected, so a typo still reaches on_accept; and a fuzzy near-miss would silently select a different value. Refusing a non-candidate is Rust work, deferred.
  • apropos is substring, not fuzzy. fuzzy_score is subsequence-based and descriptions are long sentences, so fuzzy matches nearly everything. Pinned by a fixture whose description contains the needle only as a non-contiguous subsequence.
  • One owner for *help* writes is what the seam buys — not a one-site migration. src/help.rs has renderers for command/key/buffer/mode/hook/view and none for settings, lists or apropos, and _show_help takes already-flattened text. Rendering is therefore a named per-subject function, so the future Rust work is enumerated per subject (three new renderers) rather than discovered per call site.
  • The seam-counting pin caught a real bypass: the two renamed commands were still calling the file-local show_help_text, so the funnel was fiction for exactly the two that predate it.
  • Command.predicate is still never evaluated — read only at src/help.rs:76 and one test. A preservation pin registers a raising predicate and asserts the command still runs, so a stage that starts evaluating must change that pin knowingly.

• Journey arc (P1) — Stage 1b-3 LANDED (#205) (docs/journey-stage1b3-welcome-framing.md, rev 4, three review rounds). The last of the 1b split. An unconfigured launch greets in *scratch*; M-x help renders a cheat sheet. §18 and the scorecard move Missing → Partial; §2's step-4 row stays Partial.

  • No constructor is the startup hook. EditorState::open calls new before resolving its target, the daemon constructs one too, init.lua runs inside new, and desktop restore happens later still. run()'s terminal-free prefix is now prepare_startup, and the greeting is its last step.
  • Extraction is what makes wiring testable. With the seam called by hand from tests, deleting the production call left every assertion green while shipping no welcome — the "guard with no production caller" shape. prepare_startup is pub because the journey suite is a separate crate and the rest of the sequence (run, new, open, install_state_dirs, restore_desktop_if_armed) is already public.
  • C-h is not free, and §2's step-4 row used to imply it was: it deletes a word because non-kitty terminals cannot disambiguate Ctrl+Backspace from Ctrl+H (both byte 0x08). Rebinding it to a help prefix breaks Ctrl+Backspace on every legacy terminal. Deferred to the discovery arc with the reason recorded.
  • Deliberately NOT set_generated_contents — it would lift read-only, discard history and mark the buffer generated, all wrong for a buffer step 5 requires the user to type into immediately. The one place not adopting that invariant is correct.
  • pmacs.command.invoke is not the M-x path. M-x is editor.execute-command, a minibuffer with the commands completion source calling invoke_interactive on accept — and because a selected candidate shadows typed text while accept() does session.take(), the pin asserts pmacs.minibuffer.selected() == "help" before RET.

• Journey arc (P1) — Stage 1b-2 LANDED (#204) (docs/journey-stage1b2-lsp-guidance-framing.md, rev 4, three review rounds). COHERENCE.md §1.2's canonical silence: a preconfigured language server that is not installed now reports with guidance, marks the modeline LSP:!, and appears in M-x lsp.status. §2's step-6 row stays Partial for a reason that landing did not touch: a server that starts and then crashes is still unsurfaced.

  • status_buffer_text() had existed since M4.8, exposed to Lua and tested, with no production caller and no *lsp* buffer — several src/lsp.rs and src/project.rs doc comments referred to that buffer as though it existed. Half the stage was wiring dark matter.
  • The reporting shape was already adopted twice in lsp.lua (root resolvers, notification subscribers). The canonical case was silent because nobody had converted it, not for want of a mechanism.
  • A failed spawn leaves NO record: LspManager::spawn returns early before both status_tracker.ensure and clients.insert, so pmacs.lsp.list() cannot see it and the affinity loop re-spawns. The failure therefore recurs once per file open, not once per project root as COHERENCE recorded. Hence: memoize the report, not the failure — the spawn is still retried, so installing the binary mid-session recovers with nothing to invalidate.
  • The affinity key is (language, key_uri) and key_uri is nil for markerless files, which deliberately share one server per language. Lua cannot index by nil, so one encoding function serves both tables with a u/n discriminator no URI can collide with.
  • Three tables, three lifetimes. reported (never cleared, includes the command so repointing at another missing executable re-reports); failures (cleared on a successful spawn for that key); and a buffer-keyed projection for the modeline, because that provider runs for every window on every paint and deriving an affinity key inside it would invoke root resolvers during painting.
  • A success must SWEEP the projections, not clear one. Clearing only the succeeding buffer leaves an earlier buffer rendering LSP:! while lsp.status reports nothing wrong.
  • A new per-buffer table needs its own teardown. Nothing existing reaches it: the LSP resource reconciliation iterates attachments, and a failed buffer has none by construction. pmacs.buffer.on_removed is registered once per projection; rename and delete clear rather than re-key, because after a rename the failure is no longer known to apply at the new location.

• Reap-ledger silent failures — DIAGNOSTIC, in flight (docs/reap-ledger-silent-failures-framing.md). The lane #200's framing §5 parked and its evidence unparked. Four kill(2) results are discarded in the group reap ledger, and each discard has its own consequence — three in the persistent ledger, one in the in-drain twin:

  • tick_reap_ledger's probe cannot tell ESRCH (the group is gone — correct) from any other errno (we could not ask — not correct), and retain deletes the entry either way, cancelling escalation.
  • The deadline escalation sets killed = true whether or not the SIGKILL landed, so no later tick retries it — that arm is guarded by !entry.killed and never fires again for the group.
  • shutdown()'s force-kill discards its result the same way, on the path written specifically to stop a leak at editor exit. It is not the same failure, and the difference is the retry: shutdown() iterates the ledger with no !entry.killed guard, so it does re-kill an entry the escalation arm marked. A failed escalation leaks the group until editor exit, where one more attempt is made; a failed force-kill leaks it past editor exit, with nothing left to try. Saying the escalation is "never retried by anything" collapses the two.
  • final_drain_runtime's twin collapses every errno into "dead", which quiesces the drain and cancels the readers — truncated output rather than a leaked process, and terminal for that drain where a later tick could revisit the ledger.
  • None of the four has been observed to fire. #200's evidence is an explicit SIGTERM failing in signal(), not any ledger call. What it retires is the reason ("EPERM cannot happen for our own children"), not the behaviour.
  • shutdown()'s loop exit depends on the silent drop, and this is now measured. It runs while any_running() || !reap_ledger.is_empty(), so an early exit needs the ledger empty and no live managed record — the leader-exited-survivor case the ledger exists to serve. With a failed force-kill followed by an errored probe it exits in under 500ms instead of holding its 2s bound, having concluded cleanup finished because the probe failed. Making the probe strict without touching the loop converts that silent early exit into a guaranteed 2s stall at every editor exit that hits it: the two cannot be changed independently.
  • There is no channel for a background tick to report on. ProcessEvent is keyed by ProcessId, while the ledger is keyed by pgid and is deliberately independent of managed records, so in the case that matters there is no id to attribute to. Every production consumer polls take_events(id) per known id; take_all_events would sidestep the keying but has no production consumer at all (two test call sites only). pmacs.error is dead. Reporting is therefore its own lane, as the framing's Bet 4 anticipated.
  • A test seam for a background loop has to be directed. shutdown() signals every managed process before it reaches its ledger force-kill, so one undirected "next kill fails" slot is eaten by the wrong call and the test passes while proving nothing. The persistent sites take a FIFO each (the coupling pin needs two outcomes pending at once); the in-drain site needs one outcome that repeats for a whole drain, because a one-shot is consumed by the next 1ms probe and can never survive the 50ms window quiesced requires.
  • An absence assertion needs a fixture that could have produced the thing. The in-drain pin's first fixture had no trap '' TERM, so poll_one's leader-exit group TERM killed the descendant before it wrote its late marker: the marker was absent on both paths and the pin would have stayed green with the collapse fixed. The bite caught it — the reverted seam failed only the consumed-plan check, not the content assertion. That is what the consumed-plan check is for.

• Lean 4 arc (Arc 8) — stages 1, 2, 3a, 3b, 4a, 4b ALL LANDED (docs/lean4-mode-framing.md; #160, #161, #167, #170, #179, #181). pmacs edits Lean 4: arborium-lean highlighting, a lean4 major mode, ⟨⟩ ⦃⦄ ⟮⟯ pairs, and a lake serve language server with a Lake-aware outermost root, a lazy toolchain probe, a one-shot lean --server fallback, and waitForDiagnostics. No protocol change in any stage (still v20).

  • Two of the four stages contained no Lean at all, and that is the arc's organizing rule: no PR mixes a cross-cutting substrate change with Lean feature content. Stage 2 made LSP server affinity per-project-root (ensure_server had been reusing one server across roots — a correctness bug for every language, not just Lean). Stage 3a added notification/response subscription seams to handle_server_requests, the single shared LSP event drain, plus pmacs.fs.canonicalize.
  • Two consecutive re-scouts found that rule broken by the stage being scouted — Stage 3 in round 4, Stage 4 in round 5, each time by a risk column that contradicted its own prose. The rule is not self-enforcing. Re-check every remaining stage's risk column at scout time.
  • A configured LSP root must be a canonical absolute path. It reaches file_uri_for verbatim and that URI is the affinity key, so one package opened by two spellings spawns two servers. Stage 3a's pmacs.fs.canonicalize is the primitive; it returns nil rather than a lossy path for non-UTF-8 input.
  • LspManager::stop on an already-terminal client strands it in ShuttingDown forever — server_is_live then counts it live so nothing rebuilds against it, and forget refuses it for not being terminal. Stopping a dead server is what makes it un-replaceable. Stage 3b works around it by dispatching on state (forget when terminal, stop when live); merely skipping the call leaves next_restart_at armed. The real fix is unframed substrate work.
  • elan shims lie: lake --version and lean --version can both fail ("no default toolchain configured") on a machine where Lean otherwise works, so command -v lake is worthless as a capability check. Lean acceptance is fake-server; live smokes must be PATH- and success-gated.
  • Stage 3b took six review rounds, and the same defect appeared four times: "the fallback silently doesn't happen," as no re-attach, then re-attach cleared by an unrelated buffer, then satisfied by the very server being replaced, then repairing one buffer while the rest stayed stale. Each fix was locally right; none asked what a global config swap invalidates. The durable lesson is to heal at consumption — the point where a stale record is handed out — not at the moment of the swap.
  • Stage 4a (the typed-edit consumer chain) MERGED as #179 (branch lean4-stage4a-typed-edit-chain, framing rev 8; it is part of the main anchor above). It is substrate only: builtin/runtime/typed_edit.lua owns the single buffer.after-edit subscriber and the single one-shot read, pair.lua becomes its first registered consumer, and tests/auto_pair_acceptance.rs is unchanged by zero lines (criterion 46, verified at the diff). No protocol change, no Lean content. The three decisions that turned out load-bearing rather than stylistic: consumers are called even when the record is nil (three existing auto-pair tests assert the non-event through it, and 4b abandons stale pending state on it); each consumer gets its own copy of the record, because pairing reads rec.char and a declining consumer could otherwise forge it; and the fan-out iterates a snapshot, because a consumer that registers a lower-priority one shifts itself forward under ipairs and runs twice.
  • Round 8's durable lesson: run_all_must_succeed does NOT abort the fan-out. src/hook.rs:332 collects each callback's error and continues to the remaining subscribers, marking only the run failed — so an uncontained throw inside a hook subscriber does not stop lsp.lua from flushing didChange. Two framing revisions asserted the opposite to justify a pcall. The guard was right and the reason was wrong, and by the time review caught it the wrong reason had been copied into a module comment, an acceptance criterion, a test comment, and the ledger. Correct the source a rationale derives from, not only the sites that quote it.
  • Stage 4b (the Unicode input method) MERGED as #181 (framing rev 9): a vendored 1,855-entry table generated from leanprover/vscode-lean4@17d1d08 by scripts/regen-lean-abbrev, plus a consumer registered on the Stage 4a chain at priority 50, ahead of pairing. A consumer cannot both edit and let a later consumer act on the same keystroke: the chain hands each consumer a copy of the record made before any consumer ran, so an edit invalidates every copy still to be used. The expansion therefore runs on a SECOND buffer.after-edit subscriber after the chain — which is how a pair character that terminates an abbreviation still pairs (\alp( → α()). And deferring work past a fan-out means owning which fan-out it belongs to: these fan-outs NEST, so a consumer between the expander and pairing that calls pmacs.hook.run re-enters the deferred subscriber while the outer chain is still mid-list, and the count that recognises this has to come from a MINIMUM-PRIORITY consumer — the expander is optional (a claim can stop the chain first) and a subscriber beside the deferred one is too late (the nested fan-out finishes inside the outer chain's subscriber). Its other durable facts: the table must stay an ORDERED SEQUENCE (equal-length ties resolve by source declaration order, which a pairs-iterated map cannot express); a generator round-trip check must re-read the BYTES ON DISK, because comparing in-memory strings cannot see an encoding applied by the write itself; and an expansion that SHRINKS the buffer must place the point explicitly, or every later self-insert is silently rejected and the editor looks dead.
  • Round 9 corrected three approved acceptance criteria by simulating the state machine over all 1,855 entries rather than re-reading the prose. Four review rounds over the text had not found them, because each named an example that reads as obviously right and is wrong only against the data.
  • Remaining: stages 5 (goal panel), 6 (#eval output channel), and 7 (module hierarchy) are framed but not scouted against current main.

• Inline math LANDED — #158 (docs/inline-math-slice-framing.md rev 3; merge 5aa9044). pmacs renders $…$ as typeset mathematics in the GPU frontend. No protocol change (still v20); the whole slice lives in pmacs-gpu, because pmacs-gpu depends only on pmacs-protocol and never on pmacs — a core-crate parser would have been unreachable from where rendering happens.

  • math_parse.rs → math_layout.rs → a ChunkSource::MathBox spacer chunk → per-glyph mini-buffers drawn at the shaped line's real baseline, with fraction rules as quads. Font is bundled Latin Modern Math (~717 KiB) under the GUST Font License — not OFL.
  • The v0 subset is narrow and deliberately so: Greek (34 entries), sub/superscript, and \frac. Everything else — including relations like \geq, fences, big operators, and all display math ($$…$$, \[…\]) — is a named deferral, and an unsupported command degrades the whole span back to source rather than rendering partially. In a real paper most inline spans still show source; that is the designed behaviour, not a defect.
  • Math is suppressed while the caret is inside its span, so editing always sees source. That gate reads the effective caret plus selection endpoints and is fed by three separate refresh triggers; it is the most delicate part of the slice.
  • Selection and search washes cover the whole box rectangle, not sub-ranges (sub-range washes are deferred).
  • TUI shows the LaTeX source unchanged. That divergence is recorded against COHERENCE.md §16, which audits the "no privileged frontend" rule.

• find-file LANDED — #162 (docs/dired-framing.md §10, Q#DR11; merge 2af1ab3; one review round). C-x C-f is the dired arc's Stage 0: pmacs previously had no discoverable way to open a file by path — no such command existed and pmacs.buffer.find_or_open had no interactive caller. Pure Lua in builtin/commands/default.lua, one keymap line, an 8-test dispatch-driven acceptance suite; no Rust, no protocol change. Two substrate facts it documents, both worth knowing before touching any minibuffer prompt:

  • Completion over files is flat and cannot be made hierarchical from Lua. A custom source function is called with zero arguments (minibuffer.rs:591) and runs synchronously outside any coroutine, where Handle:await() raises — so it can neither see the input to re-root on nor list a directory. Only the Rust CompletionSource::Files { root } can list, and it is single-directory and 1024-capped.
  • A selected candidate SHADOWS typed text. recompute_candidates sets selected = Some(0) whenever the list is non-empty (minibuffer.rs:372-377) and resolve_accepted_value returns the candidate over the typed contents (:564-574). So free-text accept fires only when the input filters every candidate away — for basename candidates under a subsequence filter, when it contains a /. This applies to M-x and switch-buffer too. Consequences are pinned as decisions, including the hole where a new bare name that is a subsequence of an existing entry opens the existing file, and the empty-input case (fuzzy_score gives Some(0) for an empty needle and ties break lexicographically, so dotfiles lead).
  • Also: get_or_load_buffer computes a normalized path but loads from the raw one (editor_core.rs:842-856), so a ~/… path dedups against an open buffer yet fails to load one that is not open — find-file expands the tilde Lua-side. Loading through the normalized path is a named deferral.

• dired Stage 1 — the directory view — LANDED — #165 (docs/dired-framing.md §0, S1-1…S1-12; merge c8ec8f3; one review round). pmacs now has a directory surface: C-x d / C-x C-j open a read-only listing, one buffer per directory named *dired:<canonical path>*, with a dired major mode whose mode-scoped keymap carries RET/f, ^, n/p, g, q, s. Protocol unchanged at v20. Stage 2 (marks and operations) and Stage 3 (wdired) each still need their own framing; the frozen fixture shrinks after Stage 3.

  • The Rust is confined to two things: a per-entry-tolerant read_dir (ReadDirTolerance {Fatal, PerEntry} → FsDirListing {entries, errors}), because read_dir_blocking fails a whole listing on any of five per-entry conditions and the tolerant wrapper its own module doc delegates to package authors cannot be written in Lua (one error value, no partial vec); and editor_core::normalize_buffer_path becoming pub, exposed as pmacs.path.canonicalize. Only non-UTF-8 names stay fatal — byte-preserving paths would be needed. The Lua result shape keys on errors.is_some(), so the bare array the frozen M8.2 fixture consumes with ipairs is untouched.
  • Exposing a core normalizer beat mirroring it in Lua. A Lua mirror would have been a second canonical form — the same class of bug as the five tab-width constants (#137). Applies to any future Lua-side path reckoning.
  • A fixed-width column must be fixed-width for every input. The exported pmacs.dired._layout (MARK 0, KIND 2, PERMS 3–12, SIZE 13, MTIME 24, NAME 41) is the contract Stage 3 reads offsets from, and %10d overflows at ≥10 GB, silently shifting every column right of it. Sizes now fall back to a width-clamped magnitude (K/M/G/T/P/E).
  • An ambient action must be gated on the buffer it assumes. A revert's cursor re-seat settles a tick or more later, by which time the user may have switched buffers; the paint names its buffer and is safe, but seating is ambient. This is the buffer-level instance of the rule below that interactive origin does not survive an await.
  • A failure IS an answer — don't probe first. Kinds are lstat-based in both read_dir and stat, so nothing in an entry says whether a symlink points at a directory. RET tries to list it and treats the failure as the answer; an explicit probe was a second full read_dir, so a descent listed twice.
  • Unbounded per-entry error collection needs a cap when nothing cancels the work. A dired listing carries no supersede key, so cancellation was never the backstop the tolerant loop implicitly relied on (READDIR_MAX_CONSECUTIVE_ENTRY_ERRORS = 1024).
  • This is the first builtin with mode-scoped keys (#129's first non-detection consumer), which broke the pre-existing describe_key_identifies_every_default_binding: it asserted every binding resolves through describe.key context-free, which held only while the modes table was empty. It now sets the effective context per binding and explicitly clears the mode for global ones, because a leaked mode legitimately shadows a global chord of the same name (dired's RET shadows edit.newline-and-indent), plus a floor assertion that at least one mode-scoped binding exists.
  • A dedicated panel does not carry its dedication across a descent — the framing expected it to. display_buffer never replaces the buffer in a slot dedicated to another one; it discards every side-specific parameter and falls back to the document window (Q#BP3 2.iii), and the exact-window arm errors. Dired does not unpin the user's panel; both arms are pinned.
  • Smaller facts worth knowing before touching this code: a path-backed buffer's name is its full path, not its basename, which matters for any name assertion; pmacs.buffer.kill (not remove) redirects windows off a doomed buffer first, so dired.kill-when-opening kills after the replacement is displayed; ownership is checked against the handle table only, never the buffer name; and C-x d takes no completion source on purpose (with one, RET on an empty field opens whatever sorts first, and RET-where-you-are is the gesture the binding exists for — the field is prefilled instead).
  • Verification at merge: 1,832 default + 2,009 CRDT library tests; dired acceptance 25 + 25 CRDT; the frozen m8_1 10 / m8_2 15 / m8_3 32 unchanged, which is the additivity gate for the read_dir change; M4 121; required GPU 155; isolated-XDG_CONFIG_HOME workspace sweep 3,205 across 93 suites. 15 claims bite-verified.

• Canonical main is protocol v21 (SUPPORTED=[6..=21]; v16 = ThemeFacts, v17 = FontFacts, v18 = StatuslineSegments, v19 = terminal frames/events, v20 = the GPU initial-target semantic bootstrap family, v21 = the bottom-panel band family). ADVERTISED_PROTOCOL_VERSION stays 20, permanently, and that is the activation mechanism rather than a hedge — see the Stage 2B-3 bullet. The rule for every future additive family: advertise the baseline, negotiate up from the frontend's AttachRequest. Moving the advertised version is reserved for a change that cannot be expressed additively at all, because a server-first Hello reaches a shipped frontend before it can identify itself.

• Bottom panel Stage 1 (window placement + TUI side windows) LANDED — #155 (docs/bottom-panel-framing.md rev 4; merge e745068; two review rounds). No protocol change (still v20). Arc 7's substrate: pmacs now has Emacs's display-buffer + window parameters, and a buffer can be displayed in a fixed-height window pinned to the bottom of the frame that feature code targets by policy instead of by stealing the selected window.

  • src/window.rs: WindowParams { side, fixed_rows, dedicated } plus implementation-owned quit_action / origin_document (Lua reads them, set_params refuses them); MIN_WINDOW_OUTER_ROWS = 2; Layout::compute(area, fixed) subtracts fixed children before dividing the remainder by weight, preserving last-flexible-takes-the-remainder, so a tree with no fixed leaves computes byte-identically to before.
  • Layout::compute has TWO production callers, and both must feed the same shared panel_fixed_rows map: window_placements and src/overlay_paint.rs's peer-presence pass, which derives its own text-area Rect and never routes through the first. Leaving the second on unfixed geometry paints every peer cursor at the row it would occupy with no panel open.
  • The minimum is recursive (subtree_min_rows: horizontal splits sum, vertical splits max). "Two rows at the root" does not give each nested leaf two rows. interactive_min_rows is the same recursion over the user's window.min-height preference, and applies to drag/keyboard resize ONLY — the layout pass and frame-resize reconciliation use the structural floor, so changing a preference can never invalidate an existing layout.
  • Hiding a panel is a durable state transition, not a per-frame effect (EditorState::reconcile_panel_layout): it moves focus out and releases the terminal controller, because the terminal resize path merely returns on zero content without releasing. It runs after attach/resize/display/ close and defensively before input dispatch, terminal sync, and paint.
  • FrontendView gains panel_capable, frame_geometry (None = unknown, never the GPU attach request's permanent 24×80 placeholder), and derived panel_hidden — each spelled explicitly at every construction site, preserving folding's non-Default discipline.
  • EditorCore::primary_document_window is the Q#BP14 projection seam; display_buffer is Phase 1 of the display transaction (exact target → side affinity → ordinary reuse, with option-valued height/dedication); the Lua layer owns Phase 2 (activate → hook → reconcile → revalidate → final-focus matrix).
  • Optimistic input is gated per WINDOW, not per buffer: dispatch_idle_for returns false whenever the acting frontend's active window is a side window. Marking the panel's BUFFER round-trip would be wrong — round_trip_buffers is global by BufferId, so it would disable optimistic apply for another frontend editing that buffer as its document.
  • Jump entries are per frontend and carry their origin WindowId; a stale side origin is SKIPPED, because degrading it to an active-window switch is exactly the duplicate-panel corruption the arc removes.
  • pmacs.window.display / display_file / quit / panel / params / set_params / resize / display_target, plus builtin/runtime/window.lua (window.panel-height, window.min-height, C-x ^ / C-x C-^). Adopters take display = "current" | "panel"; Stage 1 default is "current" and Stage 3 flips it.
  • The divider is the upper subtree's existing mode-line row — no row added or consumed, ui.divider restyles every exposed segment of one boundary, and drag state is HashMap<FrontendId, _> so frontends cannot steal each other's gestures.
  • open_initial_target now shares one resolve_target_buffer + exact-window install seam with display_file, and reasserts into a document window after hooks (a startup hook can now create a panel).
  • Final gates: 1,817 default + 1,994 CRDT library tests; the new bottom_panel_stage1_acceptance 46; kill ring 30; compile 67; M4 121; required GPU 152; initial-target 14 CRDT; all three vterm suites; folding Stage 2 48. All 12 CI checks green at merge.
  • Stage 2 (the GPU panel band) is COMPLETE: 2A #177, 2B-1 #184, 2B-2 #187, and 2B-3 (this lane) — docs/bottom-panel-stage2-framing.md rev 6, four framing review rounds, no open framing items; the rev-5 implementation split was explicitly approved 2026-07-27 and rev 6 records PR #184's server-first compatibility and gate correction. It reserved protocol v21 and shipped as four serial implementation slices: 2A classified census routing + per-window painter extraction (no wire change, #177), 2B-1 the wire (#184), 2B-2 the daemon projection and epoch machine (#187), then 2B-3 the GPU band, compatible v21 activation, and the negotiated panel_capable flip. Production attachment stayed v20 through 2B-2 and negotiates v21 from 2B-3 on. Parent acceptance 37–55 remains authoritative. Stage 3, the adopter default flip, is the arc's remaining step.
  • The §1.3 census is CLASSIFIED, not uniformly redirected. Only the Projection class (#1–#12, #21–#22) routes through primary_document_window; focus/input (#13–#15, #23), focus chrome and surface-routed (#16–#19), and focus/session (#20) keep their own authorities. Rerouting them breaks remote-op validation and application, DispatchIdle, presence, focused search/menu/completion routing, and terminal bell ownership.

• Bottom panel Stage 2B-1 (the reserved v21 wire) LANDED — #184 (merge 6bee09d, 2026-07-28, two review rounds plus a gate-found follow-up; all 12 checks green on reviewed head 5539b6e). It adds no producer, no consumer, and no capability: panel_capable is still false for every semantic session, so nothing about it is user-visible. What it establishes is durable:

  • Schema support and production advertisement are separate facts. SUPPORTED is now 6..=21; the daemon's unsolicited Hello still says 20. This is not a hedge — the handshake is server-first, so a shipped v20 frontend rejects a Hello { protocol_version: 21 } before it can send an AttachRequest. Bumping the advertised version is therefore an incompatible act on its own, independent of whether any new message is ever sent. A real-daemon acceptance emulates that exact rejection point and then requires the attachment to reach its initial grid. Stage 2B-3 discharged this without touching the unsolicited Hello — the advertisement is a permanent baseline and the frontend counter-offers; see its bullet below. That acceptance still passes unchanged, which is the point.
  • One shared grid validator, split along a stated boundary (pmacs-protocol/src/wire_grid.rs). Shared: checked area, the visible-cell bound (262,144), cell count, cursor bounds, glyph legality, wide-continuation topology, the 8 MiB aggregate glyph-byte budget, and the attachment rejection. Terminal-only: the 512 per-axis PTY caps, title/process metadata, selection spans, and the at_bottom == (scroll_offset == 0) coupling. Per-axis caps are a WireGridLimits parameter, not a constant, because a panel does not inherit them — a 4K surface at a small font is legitimately wider than 512 columns, and the area bound is what keeps the encoding inside the transport budget. The attachment rejection is deliberately shared: panels render no attachments either, so classifying it terminal-only would let a panel ship a cell no frontend can paint.
  • PanelFramePayload::Absent is authoritative, and silence is not. The receiver retains its last valid frame, so a close or a hide must send Absent explicitly or a stale band stays on screen indefinitely. Validation is likewise atomic — a bad frame is rejected whole and the previous valid frame is retained.
  • Two epochs, answering two different questions. panel_epoch is opaque and monotonic per frontend: stable across ordinary frames of one continuously present window/buffer, and moved on buffer replacement, new side-window creation, and every Absent → Present transition — which is what stops a stale PanelPointer from addressing a reopened panel as if it were the old one (Q#BP16). geometry_epoch answers a frontend declaration and moves whenever the frontend declares new effective cell geometry, including a font or scale change that leaves CellSize identical — exactly the case daemon-side value dedup cannot see (Q#BP2S1).
  • PanelFrame carries an explicit buffer_id (review round 1) and its focused bit is presentation and focus-chrome routing only (Q#BP14b) — the keys decision remains DispatchIdle (Q#BP14a).
  • The frontend half is FrontendEvent::{FrontendCellGeometry, PanelResizeRows, PanelPointer}, gated in both directions, with each extended enum byte-pinned on its own previous final variant so the v6–v20 encodings are provably unchanged.
  • A version bump is not done until every ratchet that pins the old version moves. The full gate — not review — found that the statusline and Vterm Stage 3 ladders still pinned v20 and rejected v21, in both structural and real-headless-probe form. Grep for the outgoing version across tests/ before calling a bump complete.

• Bottom panel Stage 2B-2 (daemon projection + epoch machine) LANDED — #187 (one review round of five findings on top of the implementation; 12/12 green; 22/22 mutations bite). What it establishes, beyond the feature:

  • A durable transition implemented as a per-frame effect is a bug shape, not a style. Four of the five review findings were one defect: a renderer-side conditional with a durable twin that disagreed with it. Wire-area exhaustion hid the rendered frame but left panel state live; a stale panel_epoch could address a reopened same-buffer panel; NoMessage cleared statusline segments it should have retained. The fix that generalizes is presentable_panel_grid — one private derivation behind both the renderer and reconcile_panel_layout_core, because two derivations of one predicate is how they drift. When touching panel rendering, ask of every conditional: is there a durable twin, and does it agree?
  • Ask what the other frontend kind's equivalent does. The semantic panel terminal missed the pre-child-drain resize its document sibling had; the repro is a 4×20 panel reporting 3×120. The new sync_semantic_panel_terminal_layout is disjoint from that sibling by construction — one resolves through primary_document_window, the other through side_window_for — so the SIGWINCH storm the original extraction prevented cannot recur through the new path.
  • A panel may legitimately be wider than a PTY. >512 columns are legal on the wire (2B-1's WireGridLimits parameter), but snapshot_for_view refused the band's content rect and the band went Absent with panel_hidden false. Clamp the terminal projection, not the band: the child takes the columns a PTY can have and the remainder is band background.
  • Mutation testing cannot reach behaviour never modelled. All 16 original mutations passed while five real defects stood; one of them even fired, removing an Absent the test asserted. Mutations prove assertions bite the code that exists. They say nothing about the assertion never written.
  • One durability hole is accepted deliberately: epoch exhaustion stays a per-frame Absent, flagged rather than hidden, because making it durable needs a new "presentation permanently unavailable" reason in FrontendView for a state requiring 2^64 presentations in one session. Stage 2B-3 did not make it cheap — the frontend half latches instead, which is a different remedy, so the daemon-side hole stays open as recorded.

• Bottom panel Stage 2B-3 (the GPU band, compatible v21 activation, and the negotiated capability flip) — the arc's Stage 2 is COMPLETE. This is the slice a user can see: a semantic GPU session now renders a real panel band instead of taking the Stage 1 non-side fallback, which is what closes the journey-steps-7–10 divergence §6 of the Stage 2 framing names. Durable facts:

  • A server-first handshake is negotiated from the CLIENT side, not by moving the advertisement. ADVERTISED_PROTOCOL_VERSION is now a permanent compatibility baseline; the frontend answers requested_protocol_version(baseline) — its own PROTOCOL_VERSION when the baseline is the current one, a verbatim echo of anything older — and the daemon records negotiated_session_version(offer). A shipped baseline frontend echoes and gets a baseline session, byte-for-byte as before; a current frontend offers up and gets the current wire. The Hello encoding and value never change, which is why the old frontend never sees a version it must reject. The daemon needed no change to accept the offer — it already recorded req.protocol_version as the negotiated version, so the whole mechanism is one value the frontend chooses plus a documented clamp.
  • The window this leaves open, named rather than hidden: a daemon whose own PROTOCOL_VERSION equals the baseline rejects an offer above its supported range. Compatibility can be preserved for old frontends or old daemons — a single AttachRequest cannot mean both "I want 21" and "≤ 20" — and the frontend direction is the one that matters, because the daemon is what a user leaves running. It closes on the next daemon restart and surfaces as an explicit GoodbyeReason::VersionMismatch naming both versions.
  • server_protocol_version split into two facts on the GPU client: session_protocol_version (what the session speaks — every wire gate keys on this) and baseline_protocol_version (what Hello said). They now DIFFER in the normal case, and that difference is the compatibility property, so both headless probe reports emit both and the two ratchets that read them assert both directions. Asserting only the session version would pass if the baseline had been bumped too, which is the exact incompatible change the mechanism avoids.
  • The GPU document bottom is three boundaries and each call site was classified individually — 20 production sites (8 status-owned, 12 document-owned), 1 definition, 8 test sites, 29 matches, arithmetic stated. geometry_capacity_bottom reserves the divider while the panel is absent (that asymmetry is what breaks the first-open cycle) while document_text_bottom costs the document nothing until a Present frame paints.
  • Moving a boundary is not always sufficient. edge_scroll_direction has no upper bound, so a pixel inside the band still read as "further down the document" and armed the document's auto-scroll — the exact named symptom, surviving a correct reclassification. Any consumer that treats "past the bottom" as unbounded needs the band as an explicit exclusion, not just a moved boundary.
  • Three of the first-pass assertions were VACUOUS, and the mutation runs are what found them. (a) The contrast assertion compared status_band_top before and after — a fixed point — so the blanket rewrite it exists to prevent moved both readings together and passed; it is now anchored to an independent formula. (b) The criterion-46 pixel test passed with the band painting nothing, because installing a panel reshapes the document and that produced the whole diff; it now counts differing pixels in the divider and cell rows. (c) The probe-versus-document-advance fixture compared two ASCII documents, which in a monospace family have identical advances.
  • "No panel frame reaches a v20 session" is defence in depth, not the placement gate. The producer's peer flag and the write-loop filter both suppress PanelFrame below the panel version independently of panel_capable, so that assertion passes with the capability gate removed entirely. The load-bearing claim is placement: the adopter's buffer must land in the pre-panel session's own document window, because a side window it cannot render is simply invisible.
  • PanelBand::presented() is the ONE frontend-side derivation of "is a band on screen" — retained valid frame, matching geometry_epoch, latch clear — behind the band inset, the painter, the hit-tester, and the drag. A latched frontend also stops absorbing payloads, so presented() is not the only thing between a disowned declaration and a painted band.
  • Panel columns come from the stable normal-face probe, never mono_advance's document-glyph fallback, and panel_cell_capacity carries the daemon's virtual status row (frontend_area_rows is total.rows - 1) with no per-axis cap, because a panel may legitimately be wider than a PTY.
  • PANEL_MIN_VERSION moved into pmacs-protocol so the GPU frontend aliases one definition instead of restating 21.
  • Stage 3 (the adopter default flip) is the arc's last step, and it is the only thing between today's state and omitting display resolving to the panel policy.

• dired Stage 2 framing LANDED (document only) — #171 (docs/dired-stage2-framing.md, revision 9; seven review rounds). Approved as a framing; no runtime code and no implementation started. Load-bearing decisions a reader must not re-derive:

  • Reconciliation is order-independent, deliberately. Reply order is not execution order — AsyncRuntime::tick drains the bus with try_recv, so a worker can finish first and be descheduled before sending. An ordering token was rejected rather than built: no static rule rescues the hazard anyway (rename dir→newdir racing delete dir/child.txt needs opposite orders depending on which ran first), and no production path can produce it. The trigger to revisit is named: the first production caller that fire-and-forgets two interdependent mutations.
  • A refused mid-edit kill is already destructive. kill_buffer clears round-trip state and moves windows before BufferRegistry::remove can return ConcurrentEdit, so editing_in_progress must be preflighted rather than relied on to refuse cleanly.
  • Path-backed buffer names are not full paths. get_or_load_buffer takes the name from the path as given and normalizes only the stored path, so a relative open is named foo.rs. Rename provenance is path-equivalence, not equality.
  • URI-keyed stores have uncorrelated writers. textDocument/publishDiagnostics is absorbed unconditionally, and mark_document_stale takes no LspServerId at all while creating URI keys across three stores. A route purge keyed on request responses cannot cover either.

• Resource-op delete-guard implementation LANDED — #190, atop the framing #186 below. The pre-filesystem refusal now exists: a synchronous apply_resource_op delete that would destroy unsaved work is refused before the filesystem is touched, rather than after.

  • A refusal that no production path can reach passes every direct-call test. The guard is asserted through the outermost user-reachable seam and falsified by revert, not by calling the check directly. This is the general rule now recorded in §5.
  • Delete refusals must be visible. Review round 2 found them silent — the operation declined and the user learned nothing. Reporting goes through pmacs.editor.set_status; pmacs.error is still a channel defined only by a test stub (§5).
  • A URI-keyed store is not one store. Purging a route keyed on request responses covers neither mark_document_stale (which takes no LspServerId while creating URI keys across three stores) nor DiagnosticView, whose URI is fixed at construction.

• dired Stage 2a LANDED — #196 (docs/dired-stage2-framing.md rev 9, §5/§6/§10 — the substrate transaction only, no dired surface). Rename and delete reconciliation across the path owners a rename actually crosses.

  • A rename is a transaction across five owners, and this is the fact that forced the 2a/2b split: the buffer path, the buffer name, the URI-keyed LSP stores plus DiagnosticView, dired's pathless handles, and a captured Lua local that no transaction can reach. Stage 2b owns everything needing new Rust primitives.
  • New LSP resource subscribers must not swallow reconciliation failures, and forget_uri must not leave purged requests live in LspClient.pending — both were review findings, both now pinned.

• Generated-buffer immutability Stage 1 LANDED — #191, adopting the contract framed in #188. dired.lua's paint and listview.lua's render write through pmacs.buffer.set_generated_contents; zero bypass_intercept writes remain in either file.

  • Why these two families first, and it is not the cheap half. compile.lua and builtin/commands/default.lua rebind all seven undo chords to a no-op; dired.lua and listview.lua rebind nothing, so a bare C-/ emptied a listing and a panel. Stage 1 closes the only two families reachable without M-x.
  • The framing owns the acceptance contract; the implementation adopts it. Review round 5 found #191 had locally restated Stage 1 criteria while #188 still carried the originals. Where an implementation finds a criterion impossible, the framing is revised and re-approved first — it is not narrowed in place.
  • Stage 2 still owes everything with new Rust in it: Buffer::apply_generated_edit, the { generated = true } option, Q#GB10's path-backed refusal, Q#GB15's identity_protected, Q#GB5's ensure_slot lock, and the remaining 13 write sites.

• Generated-buffer immutability framing LANDED — #188 (docs/generated-buffer-immutability-framing.md, revision 7; six review rounds, thirty-two findings). Revision 7 is the governing contract for the whole arc.

• Resource-op delete guard framing LANDED (document only) — #186 (docs/resource-op-delete-guard-framing.md, revision 5; five review rounds). Approved as a framing; no runtime code. It owns the urgent pre-filesystem refusal for synchronous apply_resource_op — which on main today destroys unsaved work — while #171 owns full post-delete lifecycle reconciliation. Carried facts:

  • The sequence is stat/no-op -> enumerate and validate -> mutate filesystem -> reconcile. Validation inspects without removing, so a failed deletion leaves buffers intact and on_removed still observes the path already gone.
  • EditorCore::find_buffer_for_path is the wrong lookup — it delegates to first-match-only find_by_path, and pmacs.buffer.from_file creates path-bound buffers with no dedup, so a clean first match can hide a modified second.
  • LSP does not promise batch atomicity, and pmacs advertises no workspace.workspaceEdit capability at all — no documentChanges, no resourceOperations, no failureHandling. Recovery is the client's declared choice, and there is no spec default for a client that declares none. Say only that observed pmacs behaviour resembles abort-style application.
  • pmacs.fs.remove has no dirty check of its own and neither lane adds one. After both land the guards sit one layer above it. Latent — zero production callers — but "both lanes guard deletion" reads as the primitive being guarded, and it is not.

• GPU initial target LANDED — #148 (docs/gpu-initial-target-framing.md rev 3; merge 0dd16a5; two review rounds). pmacs --gpu [--socket NAME|PATH] FILE transports exact Unix path bytes plus launcher cwd to the managed GPU client. Protocol v20 adds a semantic-session SessionBootstrapRequest after AttachRequest and an appended InitialTargetResult readiness barrier; v6–v19 wire encodings stay pinned. The daemon resolves the path lexically, deduplicates or loads/creates it in the authenticated frontend's view, runs the established load/switch hooks, upgrades the buffer for CRDT, and publishes every target-side CRDT upgrade to existing grid replicas before readiness. Semantic replicas receive a publication only when displaying that buffer, so a second target launch cannot switch an existing GPU window; one dead peer cannot fail the new session. Failed bootstrap writes a bounded result, shuts down the socket, removes provisional state, and restores the ambient active frontend. Any stale event from an uninstalled session is dropped before state access. Existing no-target managed launch, direct attach, TUI, and legacy protocol behavior remain intact. Folding Stage 2 integration: fold projection at attach is selected from the same negotiated semantic_render bit the target bootstrap uses (grid collapses, semantic/GPU stays source-line pending Folding Stage 3). Final gates: 1,815 default + 1,992 CRDT library tests; target + invocation gates 14/14 CRDT each; Folding Stage 2 48 CRDT; M4 121; required GPU 152; Vterm Stage 3 5 default + 7 CRDT; isolated-config workspace sweep 3,334 across 88 suites; two concurrent real Wayland/Vulkan GPU windows stayed on distinct target buffers after the second attach. All 12 CI checks passed.

• Folding Stage 1 (headless fold engine) LANDED — #142 (docs/folding-framing.md rev 5; merge c49a8c7; three review rounds, round 3 clean). Arc 6's engine — instance-side and headless; no frontend renders a collapse yet (that is Stage 2). No protocol bump.

  • src/fold.rs: a per-buffer FoldStore of byte ranges attached as a translating/dropping View (the BufferStyleSpanTranslator pattern — it translates strictly-inside edits and DROPS boundary-crossers, provenance-blind); FoldRegistry/SharedFoldRegistry = Rc<RefCell<HashMap<BufferId, {Arc<Mutex<FoldStore>>, ViewId}>>> (the SyntaxRegistry per-buffer model), held on both EditorCore (src/editor_core.rs:223) and EditorState (src/editor.rs:110). Containment is start-exclusive, end-inclusive (start, end]; the stored range is [end of head line, end of last hidden line] (NOT the ByteRange struct doc's [start,end)).
  • Structural source: nearest enclosing block-like node ≥2 source lines → resolve introducer↔body → derived head line (the line immediately above the first hidden line, so wrapped signatures / where clauses stay visible) → closer-aware tail (a closing-delimiter line stays visible, e.g. } else {). Stale/absent parse tree refuses.
  • The six EditorCore edit primitives call unfold_before_point_edit first (command-path pre-edit unfold, keyed on the active frontend's point). Interactive Lua-command unfold (yank/query-replace/comment) is a Stage 2 obligation; CRDT-origin unfold is Stage 3.
  • src/lua_bindings/fold.rs (install_fold): pmacs.fold.* data API (explicit buffer, no ambient resolution, matching #127) + interactive commands on the Emacs hideshow C-c @ prefix set; builtin/runtime/fold.lua.
  • src/semantic_render.rs: fold_state_msg PRODUCES FoldState (semantic/GPU sessions) — authoritative-empty, diff-suppressed, per-session baseline reset on BufferSnapshot (the #120 stale-mirror trap class; the GPU fold-mirror clear-on-snapshot is a named Stage 3 obligation).
  • Durable lesson (round 2): after wiring a cleanup into a production hook, PIN IT THROUGH THE REAL PATH — a direct-call unit test misses the wiring (falsify by revert).
  • Stage 2 (grid/daemon collapse) LANDED — #149 (merge 6ed4fe9; five review rounds; docs/folding-stage2-framing.md rev 4). Its load-bearing reframe: the TUI had no non-identity source-line↔display-row map (view_top + row was baked into ~13 sites), so Stage 2's spine is src/fold_view.rs's VisibleLineMap — derived from the fold store plus a window's line offsets, never stored — that the render loop, gutter, diagnostics, caret, selection, peer presence, viewport/scroll/motion, and the mode-line indicator all route through, plus the interactive-Lua unfold widening. Threaded as Option<&'a VisibleLineMap> on a lifetime-bearing Viewport<'a> that stays Copy. Design points the review rounds forced, each a trap for Stage 3:
    • the map's unit is a merged hidden component (overlapping or adjacent intervals unioned, keeping the earliest visible head), not a fold — folds may cross, and an inner/later fold's own head can be hidden;
    • instances are per rendered window and per command/event operation, never per frame; a command's map follows the operation's TARGET window (a wheel event names a pane without activating it);
    • fold projection is per-frontend (FrontendView.fold_projection, set at attach from the negotiated semantic_render bit) — shared EditorCore motion would otherwise make a simultaneous unfolded GPU session's cursor skip lines it still displays;
    • a hidden cursor normalizes by position, not row, and set_view_top clamps in the setter rather than being repaired at render time;
    • the interactive-Lua unfold keys on the post-intercept edit site — a managed buffer intercept may legally relocate the op. No protocol bump. Stage 3 (GPU) is next and has no framing yet; its named obligations are GPU collapse at TUI parity, caret/hit-test fold-awareness, the BufferSnapshot fold-mirror clear (parent R2-4 — the #120 trap class), CRDT-origin / GPU-optimistic interactive unfold (parent R2-3), and flipping FrontendView.fold_projection to true for semantic frontends.

• One-command GPU invocation LANDED — #141 (docs/gpu-invocation-framing.md rev 6; merge 63fbc66; two implementation reviews). The additive public path is pmacs --gpu [--socket NAME|PATH]; bare pmacs [FILE] remains the TUI. Root owns the CRDT gate, socket resolution, sibling-regular-file GPU discovery/PATH fallback, and GPU outcome. The separate pmacs-gpu binary owns connect-or-start, a five-second / 50-ms retry window, pre-winit event buffering, daemon process-group/stdin/stdout/stderr isolation, and named child reaping with explicit ownership handoff. Direct pmacs-gpu --attach RAW_PATH remains strict, is documented as advanced, and never auto-starts. No protocol change. The initial macOS/LuaJIT CI run exceeded an unrelated outline performance threshold (147 ms / 100 ms); the complete failed-job rerun passed all twelve checks before merge.

• Config registry LANDED — #127 (docs/config-registry-framing.md rev 3; merge 2e37c04; two review rounds). pmacs.config is the typed, introspectable options registry the backlog ranked first, and it closes the "config-registry-blocked" deferrals below. It was built as a PARALLEL LANE alongside vterm in a sibling worktree; the files were assigned per-lane up front and the rebase had zero conflicts.

  • Third registry beside CommandRegistry/HookRegistry (src/config_registry.rs), same R42/R50/duplicate-rejection/ SourceLocation vocabulary; Lua surface in src/lua_bindings/config.rs. No protocol change (still v18) and ZERO changes to src/editor.rs.
  • An override is ALWAYS stored, even when equal to the value it shadows; only value_epoch and listener dispatch key on effective change. The "equal-value set is a no-op" reading silently voids a buffer-local pin: nothing is stored, and a later global set flips the very buffer the user pinned.
  • Two scopes: global and buffer-local. get(name, buf) resolves local → global → default; get(name) resolves the GLOBAL CHAIN ONLY and never consults an ambient buffer. Per-language and per-project are patterns (a hook calling set_local), not scopes the registry knows about. Mode keymaps now resolve through #129, but pmacs.config deliberately remains global + buffer-local.
  • Buffer-locals live in a registry side table purged at after_buffer_removed, beside the keymap purge.
  • Listeners: commit → snapshot → drop the borrow → re-enter Lua; a raising listener is logged without blocking the rest or rolling back; a depth bound turns a cycle into a pointed error. Explicit dispose only — there is no MetaMethod::Gc anywhere in the codebase, and GC timing differs between the two Lua backends.
  • StartupOnly freezes off the existing InitCompleteFlag at write time (which is why no editor.rs call was needed). In --lib builds set_init_complete never runs, so a post-freeze test must flip the flag explicitly or it passes vacuously.
  • Adopters own their own define, so SourceLocation names the owning module: editing.auto-pair (pair.lua, read against the typed edit's SOURCE buffer), editing.trim-on-save (editops.lua, read against the buffer being saved), autosave.interval-ms (autosave.lua, re-read per tick). The migration wrappers keep their legacy coercion — the registry is strict, the legacy setters stay lenient (trim_on_save("yes"), interval_ms(1500.7)).
  • M-x describe-setting renders into *help*.

• Mode system wiring LANDED — #129 (docs/mode-system-wiring-framing.md; merge b4b925d; one review round). The existing mode-keymap substrate is now live without a protocol change.

  • Buffer.major_mode: Option<String> owns the single major mode. The detected language name initializes it once on buffer.after-load, before grammar gating, so server-only languages work; switches never rewrite it. Explicit overrides and clears survive switches. A future reload that fires after-load re-detects, and explicit mode state is not session-persisted.
  • Dispatch borrows the zero-or-one mode through Option<&str>::as_slice() and &[&str]: no hot-path mode allocation. Resolution remains buffer-local → mode → global, and registry/keymap borrows end before Lua command invocation.
  • Lua surfaces: pmacs.buffer.major_mode / set_major_mode and pmacs.editor.active_modes. pmacs.describe.key, pmacs.help.show_key, and followed percent-encoded @mode: links use the same effective context; pmacs.keymap.lookup remains raw-global.
  • The built-in mode statusline provider reads ctx.buffer, so passive splits render their own mode. Real-daemon acceptance covers all ten framing criteria across both Lua backends and Linux/macOS CI.

• Modeline language detection LANDED — #132 (docs/modeline-detection-framing.md rev 2; merge 1dd47fc). Fresh loads scan bounded Emacs -*- mode: ... -*- and Vim/Vi ft= / filetype= modelines without evaluating file content, normalize common editor aliases, and give explicit modelines precedence over inferred language.

  • builtin/runtime/syntax.lua owns one per-buffer fresh-load decision: modeline → bundled grammar extension → LSP filetype extension → exact filename → shebang. Syntax, initial major mode, pairing, comments, and LSP all reuse that pin; LSP retains its independent backing-path guard.
  • Editing a modeline or shebang does not switch an attached parser or make language-aware consumers diverge. Close/reopen re-evaluates changed file metadata. Explicit post-load major-mode overrides remain independent.
  • Bounded valid unknown names remain passive major modes without starting an unavailable parser or server. All thirteen framing criteria are covered on LuaJIT and Lua 5.4. No Rust or protocol surface changed; protocol stays v18.

• Syntax-highlight / language-detection side-quest (#114–#118) LANDED — a one-shot arc built in sibling worktrees off main while the user's themes lane (theme-faces) ran concurrently in the shared checkout. All merged. What shipped:

  • Grammars (crate::syntax::BUILTIN_LANGUAGES): every LSP-configured language now has one — cuda, bash, dockerfile (via the ABI-current tree-sitter-containerfile, NOT the dead tree-sitter-dockerfile which pins tree-sitter ^0.20), make, cmake, python, go, javascript (+jsx), typescript (+tsx), toml, zig.
  • Detection chain and pin (builtin/runtime/syntax.lua): modeline → grammar extension → LSP filetype map → filename → shebang. User-extensible Lua surfaces include pmacs.parse.modeline_aliases, .shebangs, .filenames, language_from_modeline, language_from_shebang, language_from_filename, and the pinned buffer_language. builtin/runtime/lsp.lua delegates to that shared decision after enforcing its backing-path requirement. Grammar name MUST equal the pmacs.lsp.config.<name> key. A buffer keeps its pinned language across edits/switches; close/reopen performs a fresh bounded inference.
  • LSP configs added: dockerfile (docker-langserver --stdio), cmake (cmake-language-server, config via init_options.buildDirectory="build" — it does NOT pull workspace/configuration). Make has no server.
  • Substrate: LanguageEntry.highlights_query and .locals_query are &[&'static str] fragments joined base-first (cuda over c/cpp; ts over js/jsx). Since locals-query processing #134, settle compiles the grammar's LOCALS_QUERY, resolves Tree-sitter's scope/definition/value/ reference conventions into sorted LocalFacts, and stores them beside each layer's tree/query. Work runs once per fresh bundle and only when the highlight query asks about local; viewport rendering remains bounded. Both TUI and semantic/GPU producers evaluate #is?/#is-not? local through the shared capture walk. Non-shadowed JS/TS builtins are restored; shadowed definitions/references keep ordinary variable styling.

• Multi-language injections (#122) LANDED — the direct continuation of the #114–#118 highlight arc; four review rounds, framing docs/multi-language-injections-framing.md (Q#IJ1–IJ11). A buffer can now hold more than one language: ParseTreeBundle holds Vec<Layer> (root + injected children, depth-ascending, installed atomically so the existing StyleGate + highlight-cache Arc gates still work). The parse worker builds child trees off the static BUILTIN_LANGUAGES table (lazy load preserved) via set_included_ranges — child node offsets are ABSOLUTE, so injected spans are buffer-coordinate-native; settle resolves each layer's highlight query (SyntaxRegistry::resolve_layer_queries). First consumers: markdown fenced code + markdown_inline (retires the M9.7 block-only floor). New substrate: LanguageEntry.injections_query; default_injection_aliases + SyntaxRegistry::injection_alias_snapshot (case-folded fence names, Lua-extensible via pmacs.parse.injection_aliases, snapshotted into ParseRequest so the worker never touches the Rc registry or Lua); ParseTreeBundle.injection_capped (the 4096-layer backstop, surfaced once/buffer via pmacs.error at settle); compute_highlight_spans_for(query, tree, source, local_facts, range) (per-layer); the wire flatten_layer_spans event-sweep → DISJOINT effective spans (deeper / later-sibling / narrower wins, keyed by (layer_index, capture_order)); GPU spans_from_segments + source_color_at fold. Two findings to keep: injection ranges exclude only NAMED children (anonymous tokens ARE the injected text — excluding them shreds a block inline node; matches tree-sitter-md's own splitter), and the wire flattener runs over the WHOLE buffer via the file-style summary, so it must be an event sweep, not O(spans²).

• JSON + YAML grammars and language servers (#123) LANDED — bundled ABI-current tree-sitter-json / tree-sitter-yaml cover .json, .yaml, and .yml; the existing injection engine now highlights YAML frontmatter and JSON/YAML fences. Default external LSP configs are the pinned vscode-json-language-server provider and yaml-language-server; configured settings are pushed after initialized, which also supports push-model servers. The fake-server delivery proof and PATH-gated live JSON/YAML provider smokes cover the configuration contract. .jsonc / .json5 remain a deliberate follow-up because the JSON grammar is strict.

• Compile-mode (Arc 5 stage 1, #113) LANDED (2026-07-14, 7 rounds; framing docs/compile-mode-framing.md rev 13). compile.run streams /bin/sh -c "exec 2>&1; <cmd>" into an intercept-read-only *compilation* buffer via a Lua ANSI parser; once-per-newline error rules; unified error.next/error.previous (M-g n/p, C-x `, M-!). Substrate other code can use: ProcessSpec.stdin/group (group lifecycle: reap ledger, in-drain enforcement, cancellable poll readers), buf:revision(), jump_back fires buffer.after-switch, pmacs.errors.claim, AnsiParser::finish() (observable reset), and the style-overlay stack: buffer-attached BufferStyleSpanTranslator (once-per-edit, fragment-preserving), render-only window overlays with identity-deduped Window::ensure_overlay + clone_for_split, idempotent atomic handle:dispose().

• Editing-conveniences pack (editops, #111) landed (framing docs/editing-conveniences-framing.md rev 6). goto-line, case ops, transpose, zap-to-char, line move/duplicate/join, region sort/reverse/dedupe, delete-trailing-whitespace + opt-in pmacs.editops.trim_on_save. Substrate: pmacs.killring.kill_range / break_chain([fid]) / arm_kill_prompt+commit_kill_prompt (marker lifecycle), and the origin-guard pattern for chain-sensitive minibuffer commands.

• Auto-pairing (#110) landed — Arc 2 COMPLETE (framing docs/auto-pairing-framing.md rev 6). BUILTIN_PAIR_CHARS in pmacs-protocol leave both frontends' optimistic classifiers; builtin/runtime/pair.lua loads BEFORE lsp.lua (first-didChange ordering contract); one-shot typed-edit provenance via pmacs.editor.take_typed_edit() (buffer-revision postcondition, Q#AP9). Substrate: buf:path(), pmacs.lsp.buffer_language(buf), PMACS_FAKE_LSP_CHANGE_SINK, TestDaemon::spawn_with_config.

• Themes (Arc 4) stages 1–3 LANDED; Arc 4 COMPLETE ON main.

  • Stage 1 (#120, docs/theme-faces-framing.md rev 9): named UI faces as reserved ui/ui.* theme entries; transactional split syntax/face epochs; protocol-v16 ThemeFacts; snapshot/baseline symmetry; store-sourced diagnostic-count freeze.
  • Stage 2 (#124, docs/gpu-set-font-framing.md rev 5): pmacs.gpu.set_font and authoritative protocol-v17 FontFacts; frontend-local family resolution, live font reload/reflow, and visual-run caret geometry.
  • Stage 3 (#125, statusline-segments, docs/statusline-segments-framing.md rev 3): composable strict pmacs.statusline providers; borrow-released per-window evaluation with failure latches; legacy-preserving TUI composition; a pure built-in LSP provider; dynamic modeline faces; protocol-v18 StatuslineSegments; authoritative-empty/snapshot symmetry; and atomic GPU validation, face resolution, shaping, clipping, and cache invalidation. Acceptance 1-27 is implemented. Final gates: Clippy clean; 1,619 default + 1,793 CRDT library tests; 7 default + 8 CRDT feature acceptance; 114 M4; 109 required GPU; one-invocation workspace sweep 2,718 passed across 78 suites (19 ignored, basedpyright filtered); git diff --check clean. Stage 3 landed as #125 and completed Arc 4 on main.

• Vterm Stage 1 terminal core LANDED ON main — #126 (docs/vterm-framing.md rev 5; merge 643d1e1).

  • Implementation commits: bbc1f33 (Stage 1), 962944b (Darwin signal normalization), first-review fixes f0a235f, 28f2e6c, bf972a7, and second-review hardening 9797ada; reviewed feature head fc4e0ce merged through PR #126, https://github.com/levineuwirth/pmacs/pull/126.

  • AnsiParserProfile::{LineOriented, FullScreen} preserves compile/REPL behavior while terminal PTYs emit the full cursor/mode/device operation set. src/terminal/{screen,input,session}.rs owns the state machine, encoders, and lifecycle registry.

  • Public session seam: owned strict TerminalSpec; owned TerminalSnapshot; TerminalProcessState; and SharedTerminalManager = Rc<RefCell<TerminalManager>> with open/is_terminal/process_id/snapshot/tick/send/resize/terminate/prune/ shutdown. Stage 1 snapshots are context-free; Stage 2 adds per-view state without a second screen.

  • EditorState tick order is supervisor → terminal-owned PID drain/prune → process.after-tick. Terminal IDs are not exposed through pmacs.process; ordinary Lua/LSP/MCP ownership is unchanged. Terminal identity buffers are pathless, clean, empty, round-trip, and guarded read-only at every rope/CRDT/history mutation boundary.

  • Acceptance 1–14 is mapped in the framing. The real PTY bite splits ESC/CSI writes, observes alternate-screen cursor addressing, blocks and resumes through raw send, restores the main screen, and pins final output before exact PID/outcome annotation. One-row annotation visibility, TERM-ignoring shutdown, spawn rollback, buffer-kill prune, and immutable empty CRDT bootstrap are pinned.

  • Review round 1 added typed IND/NEL/RI with margin-correct screen behavior, defaults absent TERM to xterm-256color, makes shutdown liveness acceptance portable with kill(pid, 0), and preserves custom tab stops on resize. Review round 2 rejects C0/C1 controls before they enter screen cells, preserves the released button code in SGR mouse reports, removes dead screen paths, and clears stale round-trip state during prune. Stage 2 now uniquifies default terminal buffer names transactionally.

  • Exact CUU/CUD and out-of-range DECSTBM clamping, combining across controls, xterm alternate-screen details, legacy non-SGR mouse, printable ASCII and CSI-dispatch allocation fast paths, and scrollback-cap naming are explicit post-arc deferrals in the framing.

  • Final from-start rerun after review round 2: Clippy clean; 1,661 default + 1,837 CRDT library tests (3 ignored each); 9 default + 10 CRDT vterm acceptance; M4 114 passed (3 ignored, 1 filtered); required GPU 109; workspace 2,769 passed across 79 suites (19 ignored, 1 filtered); diff check clean. scripts/bite HEAD^ src/terminal/screen.rs --test vterm_stage1_acceptance terminal_cells_reject_child_control_characters is a clean behavioral bite. The parser dispatch has its independent clean behavioral bite; the original main/crate-root bite remains explicitly weaker compile-time API evidence.

  • Stage 3 GPU/protocol LANDED ON main — #135 (merge cac4961; docs/vterm-framing.md Revision 9, criteria 28–37). Protocol v19: InstanceMessage::TerminalFrame (discriminant 26, daemon-gated) plus FrontendEvent::TerminalResize (11) and TerminalPointer (12), both frontend-gated — the first bump gating in BOTH directions. SUPPORTED=[6..=19].

  • pmacs-protocol/src/terminal.rs now owns the shared terminal bounds, TerminalProcessState, TerminalSelectionSpan, and the single structural policy TerminalFrame::validate; src/terminal/* re-exports them so no duplicate type exists. unicode-width is a workspace dependency so the screen and the validator measure glyph columns identically. MAX_TERMINAL_FRAME_GLYPH_BYTES = 8 MiB bounds the payload instead of widening the transport cap; the measured maximum legal frame encodes to 13,437,863 bytes under the unchanged 16 MiB MAX_FRAME_BYTES. Over-bound snapshots are rejected, never truncated or silently chunked.

  • The Viewport gate keys on the AUTHENTICATED SOURCE'S ACTIVE BUFFER, not the buffer the message names. Viewport also aligns the window to the buffer it declares, so a stale document viewport in flight when a command opens a terminal drags the frontend back off it

    • the terminal then never paints, with no error anywhere. The weaker "is the declared buffer a terminal" reading looks right and fails exactly this way.

  • Suppression compares the COMPLETE ordered payload, never screen_generation: scroll, selection, viewport, and process state all change without advancing it.

  • GPU: pmacs-gpu/src/terminal.rs is a pure cell-space paint planner (testable without a GPU); the renderer builds one shaped buffer per text run so a wide/cluster advance can never choose the next column's origin. pmacs-gpu --headless-probe drives the real attach client without winit (attach::connect_with_sink), which is how criterion 37 gets one real daemon + real PTY + real wgpu path.

  • #135 integrated canonical main after #137 landed. The one code conflict joined TAB_STOP_COLUMNS with the terminal imports in pmacs-gpu/src/main.rs; terminal geometry remains fixed-cell and never consumes the document tab-stop projection.

  • Final post-integration gates: strict Clippy; 1,768 default + 1,944 CRDT library tests; Vterm Stages 1/2/3 at 9/10, 4/4, and 5/7 default/CRDT; statusline 7/8; tab-width 2/2; M4 121; required GPU 139; workspace 2,946 passed across 84 suites; formatting and diff check clean. The first macOS/LuaJIT CI run timed out waiting for VTERM_ALT_READY in the Stage 2 real-TUI smoke; the complete failed-job rerun passed all 12 checks.

  • Stage 2 TUI LANDED ON main — #130 (merge 86fc1bc; docs/vterm-framing.md Revision 7, criteria 15–27). TerminalViewKey keys per-frontend/window projection state over one shared process/screen; logical row anchors retain

    scroll/selection through reflow. One authenticated frontend controls at most one session, with atomic replacement and release on focus/switch/kill/detach.

  • The strict pmacs.terminal Lua surface owns open/state/view/send/terminate and context-implicit scroll/copy commands; the latter error unless the invoking frontend's active window is a terminal. Fixed C-c is the per-frontend terminal escape: only its next key reaches terminal-local editor bindings, while unescaped bound keys pass through to the child. C-c C-c sends one literal interrupt. Copy drains through the acting frontend's clipboard path; active BELs drain once locally and per daemon frontend, while historical/passive bells are baseline-suppressed.

  • TUI composition paints owned terminal cells/styles only inside each window's content rectangle, suppresses document overlays, and keeps sibling splits independent. Daemon key/mouse/paste/focus/resize/detach routing uses the authenticated connection source rather than client-claimed IDs. builtin/runtime/terminal.lua provides the terminal command, view commands, and pure ui.modeline.terminal process/scroll segment.

  • tests/vterm_stage2_acceptance.rs maps Lua transactionality, shared-view isolation, clipboard/modeline behavior, and a hermetic real /bin/sh TUI PTY smoke. Stage 2 changed no wire schema or GPU renderer; protocol remained v18 until Stage 3.

  • PR #130 review round 1 (8702791) aligned dispatch with the approved escape-prefix contract, closed the non-terminal Lua error path, made controller replacement atomic, retained zero-area view anchors, removed duplicate detach work, and replaced per-view deep scrollback clones with borrowed live/published row projections. Focused child-input coverage pins both unescaped bound-key passthrough and C-c C-c.

  • PR #130 review round 2 (b9a7e40) clamps anchors into the first surviving cell when eviction cuts through a wrapped logical line, prevents ambient active_frontend from minting interactive Lua authority, names malformed explicit-context fields, restores dispatcher rationale, and removes owned cell snapshots from terminal mouse routing. The framing now records the transient v18 semantic-controller boundary and bracketed-paste injection deferral.

  • Current-main integration (3f0252f) preserved per-frontend terminal dispatch while applying the landed mode-scoped keymap, and exposed the mode, terminal, and lsp statusline providers together. PR #130 merged at 86fc1bc.

  • Final integrated gate: cargo fmt --check; strict workspace Clippy; 1,753 default + 1,929 CRDT library tests (3 ignored each); mode-system acceptance 1 default + 1 CRDT; Stage 1 acceptance 9 default + 10 CRDT; Stage 2 acceptance 4 default + 4 CRDT; statusline acceptance 7 default + 8 CRDT; M4 114 passed (3 ignored, 1 filtered); required GPU 109; workspace 2,882 passed across 82 suites (19 ignored, 1 filtered); git diff --check clean.

• Tab-width rendering parity LANDED — #137 (merge 2625ec7; docs/tab-width-parity-framing.md rev 2). Source tabs remain one byte while every buffer renderer follows the shared fixed pmacs_protocol::TAB_STOP_COLUMNS = 8.

  • src/display_width.rs owns allocation-free Unicode/tab-aware byte-to-column accounting for plain text, syntax, diagnostics, completion anchors, buffer-style overlays, and search washes.
  • The GPU rich-chunk projection expands source/adornment tabs before cosmic-text shaping and retains first-class source-tab provenance. Carets, hits, selections, peer washes, and diagnostic geometry share the same source/projected boundary rules, including a soft wrap inside one expanded tab.
  • GPU minimap widths use the same tab/Unicode rule and refresh in the accepted text-edit transaction. No config, wire shape, negotiation, or protocol version changed. Local gates: 1,763 default + 1,939 CRDT + 1,763 Lua 5.4 library tests; 2 focused acceptance; M4 121; required GPU 119; workspace 2,911 across 83 suites; strict Clippy and diff check clean.
  • This closes the standing "tab width is a rendering-parity bug, NOT a config gap" deferral in §5: one shared constant now drives every renderer. Terminal cells are deliberately OUTSIDE it — a terminal's columns come from the child, so pmacs-gpu's terminal geometry uses the monospace advance and never TAB_STOP_COLUMNS.

• PARKED: kill-ring browser + persistence. Revision 2 framing is preserved on branch kill-ring-browser, but its 0efb5cd scout is stale and must be repeated before implementation. No PR or implementation is active.

• Roadmap: docs/roadmap-2026-07.md (ranked arcs). Position:

  • Arc 1 (LSP utility surface) COMPLETE — completion popup (#92/#93), panels/references/outline/hover (#94–#96), plus hardening follow-ups (#102, #105, #106).
  • Arc 2 (editing table stakes) COMPLETE — query-replace (#97), kill ring + M-y (#103/#105/#106), comment-toggle (#107), auto-indent (#109), auto-pairing (#110).
  • Arc 3 (persistence) COMPLETE — saveplace/recentf (#98), desktop-save (#99), autosave/crash-recovery (#100), save-clobber fix (#101).
  • Arc 4 (themes + extensibility) COMPLETE — named UI faces (#120), live GPU font preferences (#124), statusline providers (#125).
  • Arc 5 terminal stage COMPLETE — compile mode (#113), Vterm terminal core (#126), TUI frontend (#130), and protocol/GPU Stage 3 (#135) landed.
  • Config registry COMPLETE (#127) — not a numbered arc; it was the cross-cutting substrate ranked first on docs/side-quest-backlog.md's north star, and it unblocks the editing/indent/comment items that were config-blocked.
  • Mode system wiring COMPLETE (#129) — major-mode keymaps, introspection, lifecycle initialization, and statusline display shipped.
  • Locals-query processing COMPLETE — #134 — grammar locals metadata, lexical resolution, settled per-layer facts, shared TUI/GPU local-predicate filtering, and a registry-wide locals-query invariant shipped without a protocol change.
  • Arc 6 (folding) Stages 1 and 2 LANDED — #142 and #149 — the headless fold engine (store, structural source, Lua C-c @ surface, command-path unfold, FoldState production), then the grid/daemon collapse (the VisibleLineMap spine, fold-aware gutter/diagnostics/caret/selection/ presence/viewport/motion, and the interactive unfold widening). Stage 3 (GPU) is next, unframed.
  • Web grammars HTML+CSS LANDED — #146, and LaTeX Stage 1 — #144 with its inline-math parent framing #145.
  • Arc 7 (bottom panel) Stage 1 LANDED — #155 — window placement, window parameters, TUI side windows, the divider, and the adopter display opt-in. Stage 2 (the GPU band) is next and needs its own re-framing; Stage 3 is the default flip. DAP was parked awaiting exactly this arc's Stage 1 and can now re-baseline its touch census.
  • Remaining ranked arcs: 6 folding Stage 3, 7 bottom-panel Stages 2–3, DAP, 8 GPU splits, plus the .ipynb arc (its JSON-grammar prerequisite shipped in #123).

• GPU terminal input LANDED — #166 (main @ b889873; docs/gpu-terminal-input-framing.md rev 2; one review round). The dispatcher applied both terminal-layout syncs to every attached frontend each tick. A semantic session satisfies both conditions — a term_sizes entry from AttachRequest and a terminal declaration — so its PTY was resized twice per tick forever: the grid arm installed the TUI placement size, the semantic arm the declared content rectangle, each arm's old_size == size guard seeing only what the other had just written. The child took a SIGWINCH storm at tick cadence, which made typing into a GPU terminal impossible while output kept flowing. TUI was structurally unaffected.

  • EditorInstance::sync_terminal_layout is split into sync_terminal_controller_liveness (frontend-kind neutral: panel reconcile + release of a controller whose window moved away — reads only views/windows/controller, never a grid size) and sync_terminal_grid_geometry (grid only: TUI placement + resize). sync_terminal_layout survives as the composition, so editor::run and LOCAL are byte-identical.
  • daemon::sync_terminal_layouts_for_tick is the extracted loop body: liveness for every frontend once per tick, then exactly one geometry arm keyed on semantic_states membership — the same fact session establishment uses, so the arms cannot both fire.
  • The trap, kept in a comment: the release on a missing window_placements entry reads like liveness and is grid geometry. A semantic frontend has no placement entry at all, so moving it into the neutral half would release a GPU controller every tick.
  • Why not the one-line guard: the grid arm was also the only per-tick controller-liveness release a semantic frontend got, and sync_semantic_terminal_layout cannot take it over — the buffer-follow snapshot clears the viewport declaration, so that arm stops running in exactly the switch-away case that needs the release.
  • No protocol change (v20). Gates: 1,829 default + 2,006 CRDT library tests; vterm Stage 1/2/3 10/6/9 CRDT; bottom-panel 46; M4 121; required GPU 155; isolated-config workspace sweep 3,177 across 92 suites.
  • Known gap, its own lane: CI never enables crdt, so the Stage 3 real-path acceptance (including a37) is not compiled there. #166's unit pins are not crdt-gated and do run. See docs/active-work.md.

2. How we work (the part that must not drift)

The user is expert and reviews deeply — they falsify framings and find real bugs in round after round. The cadence that has worked for ~40 PRs:

1. Scout ground truth in the code before proposing anything.
2. Write a framing doc — docs/<feature>-framing.md, numbered decisions (Q#XY1…), explicit "Ground truth", "Bets", "Deferred (named)", and an acceptance-test list. Present it and wait for explicit approval ("Go for it" / "Ready to roll"). Expect 1–3 rounds of findings first; revise the doc, don't argue.
3. Branch off main (one feature = one branch = one PR). Commit the framing as the first commit.
4. Implement. Every reviewer finding gets a bite-verified fix — a test that fails without the fix. Watch for vacuously-passing tests.
5. Run the full gate suite (§3). Open the PR with gh.
6. The user replies with "Findings" lists on the PR rounds too. Same discipline. They say when to merge — never merge unprompted.
7. After merge: update this handoff + your memory.

Commit/PR conventions: commit messages via git commit -F <file> (no inline backticks through the shell). Authorship trailers and PR attributions must be truthful: do not add a Claude co-author trailer or Claude Code attribution unless Claude actually contributed. Clippy runs as its own step, never &&-chained.

3. Gate suite (all green before any PR)

cargo fmt --check
cargo clippy --workspace --all-targets -- -D warnings   # own step
cargo test --lib                                        # ~1500
cargo test --lib --features crdt                        # ~1672
cargo test --test <the new/touched acceptance suites>
cargo test --test m4_acceptance -- --skip basedpyright
PMACS_REQUIRE_GPU=1 cargo test -p pmacs-gpu             # 58
cargo test --workspace -- --skip basedpyright           # full sweep
git diff --check

Machine-specific caveats — re-verify on a machine you haven't used before trusting them:

• Ambient storage roots: control all FIVE, not four. Until the ambient-root isolation lane lands (docs/test-ambient-config-isolation-framing.md), the ~96 integration suites read the developer's real ~/.config/pmacs/init.lua and write bundled packages into the real data root: #[cfg(not(test))] guards the crate's own unit tests only, and EditorState::new materializes packages outside every cfg guard. A local full-suite run therefore needs, all pointed at a fresh directory:

  XDG_CONFIG_HOME  XDG_DATA_HOME  XDG_STATE_HOME  XDG_CACHE_HOME
  PMACS_STATE_HOME
  

  The fifth is not redundant. PMACS_STATE_HOME outranks XDG_STATE_HOME (src/state.rs), so redirecting the four XDG variables on a machine that exports it leaves the real state root live. HOME is deliberately left alone: it is the fallback for the XDG roots (already covered once they are set) and separately drives ~-expansion, which find_file_acceptance pins on purpose. A run isolating only XDG_CONFIG_HOME stops the init.lua reads and still writes through the real data root — every local gate run in this repo before 2026-07-31 had that hole.

  After the lane lands the in-process population isolates itself through EditorState::new_with_roots(&crate::iso::roots()) and the five variables are belt-and-braces rather than required.

• basedpyright: the desktop binary was never broken — this was a real code defect, diagnosed and fixed 2026-07-29 (see §5, "A Drop body runs before its fields"). RuntimeHandles::drop joined its reader threads before the stdin field dropped, so the server never got stdin EOF, never exited, and kept the output pipe the readers were blocked on. Deterministic on the desktop, invisible on the laptop and in CI, which is why it read as a broken local binary for weeks. How the orphan is actually made — WE make it. basedpyright's console script runs bundled node through subprocess.run and waits (nodejs_wheel/executable.py:50, verified in 1.39.6). At teardown shutdown() SIGTERMs the recorded pid — the Python wrapper — which dies without forwarding the signal, orphaning node to PPid 1 holding the pipes. An earlier revision of this entry said the wrapper "spawns node and exits"; that was wrong, and the refutation was already in hand, since the initialize handshake succeeds, which a wrapper that exited at spawn could not have done. The consequence is for the follow-up, not the fix: the orphan-management work is stop orphaning them (signal the group), not tolerate self-orphaning. The --skip above stays for now: it is still correct on any tree predating the fix, and — the one live reason — CI never installs basedpyright at all, so arming PMACS_REQUIRE_PYRIGHT would fail rather than test anything. The two original reasons are both gone: the hang is fixed, and #195 gave every job a timeout-minutes, so a hang can no longer burn six hours. Installing basedpyright in CI (a uv plus bundled-node download per leg) and dropping the local skip are two separate proposals, each owed its own evidence.

• GPU on the laptop: AMD Radeon 780M (RADV) — native Vulkan, PMACS_REQUIRE_GPU=1 works without lavapipe.

• Flaky-under-load tests — what this lane OBSERVED. (Historical record. This bullet no longer states a triage rule: for judging a red run, docs/ci-red-signatures.md is the authority, and its rule supersedes "rerun isolated" — a green rerun establishes intermittence only, never environmental cause. m6_8_supervisor_reaps_all_children_across_cycles is A2 there — an audit note, not a matchable row, because no signature was ever captured.) The m8 daemon tests and the m6 process/PTY tests (m6_1_pty_mode_lifecycle_started_then_exited, m6_8_supervisor_reaps_all_children_across_cycles) are timing-based; editor::composition_overhead_under_ten_percent is a render-ratio microbenchmark that fails ~1/3 even isolated single-threaded (already cfg!(macos)-disabled). (Local measurements, 2026-08-05, 16-core Linux, tree-primitive branch, which could not reach it — its diff versus main touches no src/, no crate, no manifest. Two reds, both inside the full --features crdt lib run, at dispatch overhead 30.7% and 10.3%; two full-suite runs at the same tips were green; and 10/10 green run alone, ratios spanning -2.3% to +1.5%. So the in-suite/isolated split has now been seen twice, and the second red cleared the 10% budget by 0.3 points — the threshold is marginal, not comfortably clear. Recorded as measurements, NOT a cause: ten isolated greens establish that the ratio sits nowhere near the threshold when alone, not that in-suite contention is what pushed it over, and two reds against two greens in-suite is intermittence rather than a mechanism. Not a ci-red-signatures.md row either — that registry judges red CI runs, and these were local.) Vterm Stage 3's merge CI saw one macOS timeout in real_tui_terminal_smoke_restores_host_after_output_input_resize_scroll_copy_and_bell; the complete failed-job rerun passed. The required-GPU gate also failed once in headless_diag_face_recolors_band_counter_despite_unchanged_text, then passed both an isolated single-thread rerun and the full 139-test rerun. (That "rerun the test alone before investigating" instruction is retired — an isolated green reproduces nothing about a load-sensitive failure and establishes intermittence at most. See the registry's rerun rule.) Run the workspace sweep as ONE cargo test invocation piped to a full log — a double invocation + grep -c "test result: ok" can mask real failures with a misleading 0.

• GPU tests need a Vulkan device. PMACS_REQUIRE_GPU=1 makes absence a hard failure instead of a silent skip. Headless option: lavapipe (see docs/repository-audit-2026-07-03.md for the CI harness how-to). On a laptop without discrete GPU, mesa/lavapipe works.

• The desktop's shell is fish (no $(...), use (...); no $UID, use (id -u)). Check $SHELL here before assuming.

4. Substrate invariants (do not undo; tests enforce most of these)

Generated buffers: Buffer::set_generated_contents is the ONE authorized write (terminal copy mode #178) — lift read_only, replace via a single whole-buffer Replace skipping intercepts, discard history, re-assert read_only, and return the Edit. Three things make it a unit rather than a convenience:

• An intercept is not read-only. Buffer::undo reaches the rope through ensure_writable and never consults the intercept chain, so an intercept-only "read-only" buffer is emptied by M-x buffer.undo. Rebinding the undo chords buffer-locally does not close it — compile.lua's own comment says so ("command/menu undo stays dispatchable"). Only rope-level read_only does.
• A bare set_read_only would be worse than nothing, because it also refuses the owner's refresh — the operation such buffers exist for. That is why the pairing, not the setter, is the primitive. There is deliberately no Lua set_read_only.
• A rope write is only half of an edit. The returned Edit must be fanned out (notify_buffer_edit_to_windows, which also queues the daemon-origin CRDT op). Skip it and a displaying window keeps a TextView line index describing the previous contents — the next paint indexes the new rope with stale ranges and trips assertion failed: end <= self.len() — while replica mirrors never import the write at all.

History clearing is load-bearing twice (nothing can pop entries read_only makes unreachable, so they leak), and must clear whichever history the buffer has: the v0.1 stacks are bypassed in CRDT mode, where it lives in loro's UndoManager. That has no clear, and needs none — a manager records only what happens after construction, so CrdtState::clear_undo_history rebinds a fresh one to the same doc.

Not yet adopted — the inventory is four writer mechanisms covering five buffers. Every remaining intercept-protected writer uses the older idiom: an erroring intercept plus set_round_trip_input, written through bypass_intercept, with the rope left writable. All are emptiable by M-x buffer.undo:

writer	buffers	shape
builtin/runtime/listview.lua:60-61	every listview panel	delete-all + insert
builtin/runtime/compile.lua (ensure_slot)	*compilation*, *shell-command*	append per output batch
builtin/commands/default.lua:869	*search-results*	reset per query, then append per match batch
builtin/runtime/dired.lua:371	every dired buffer	whole-buffer replace

Do not read ensure_slot as covering the search panel — it serves *compilation* and *shell-command* only (compile.lua:1090,1125). *search-results* is an independent panel with its own intercept, round-trip mark and writes, and compile.lua names it only in a predicate. Nor is the scope "every generated buffer": *workers*, *help* and *buffer-list* are generated too but do not use this idiom, and the REPL package's intercept (builtin/packages/repl/init.lua:187) is an op-filtering editing policy, not a read-only panel — neither group belongs to this lane.

Adoption is not a one-line swap. It inherits the fan-out obligation, and the three appending buffers need a streaming variant of the primitive; listview and dired already write whole-buffer replaces and are the cheap half. Recorded in COHERENCE.md §14.

And it does not replace set_round_trip_input. The protection is layered across two copies: rope-level read_only refuses the op at the daemon; round-trip input stops a semantic frontend applying optimistically to its own mirror, which a daemon-side refusal cannot reach — the refusal arrives after the frontend has already painted, so it buys divergence, not prevention.

Command boundaries (Arc 2 kill-ring substrate) — EditorCore.command_history: HashMap<FrontendId, CommandBoundary{this, last}>, per frontend. Rotate on: keybound command, self-insert, menu invoke, invoke_interactive (the M-x path). Break on: unbound key, GPU optimistic CRDT edits, pointer gestures (wheel scroll deliberately does NOT break), unified paste. Plain pmacs.command.invoke stamps nothing (programmatic API); invoke_interactive rotates-then-invokes (Emacs M-x semantics). Single-codepoint optimistic CRDT inserts classify as buffer.self-insert (exact decode; "a(" breaks instead). Lua: ed.this_command() / ed.last_command().

Effective-edit returns — buf:insert/delete/replace return the post-intercept (start, end, inserted_len). Callers that care (killring, comment) compare EXACTLY against the request; length-delta and text-at-position checks are documented defeated patterns. Always pcall the mutator: a rejecting intercept must report, not throw through, and failed ops must leave no state (kill chains, yank sessions).

Kill ring — entries {id, text} with stable monotonic ids; chains and yank sessions are per-frontend and id-checked (an index is not stable under other frontends' pushes). OS clipboard mirrors to the acting frontend only. Paste is a unified daemon arm keyed by the dispatcher's AUTHENTICATED source — never a payload frontend_id.

LSP outbound positions — every Position/Range builder in src/lsp.rs routes through outbound_position (byte → negotiated encoding). Any new request builder must too; UTF-16 servers reject raw byte columns on non-ASCII text. Semantic tokens: full, full.delta, and range are three INDEPENDENT capabilities — gate each.

Persistence (Arc 3) — state-dir wiring lives in install_state_dirs() on real entry points only, NOT EditorState::new() (tests stay hermetic); PMACS_STATE_HOME overrides. Autosave: one buffer owns a path's recovery slot; only recover/discard release unclaimed crash data; adopt clears the old owner's skip cache.

Protocol — encoding-breaking bumps are deliberate and versioned. Canonical main is [6..=20]. The in-review bottom-panel 2B-1 schema extends support to [6..=21], while ADVERTISED_PROTOCOL_VERSION stays 20 until 2B-3 provides compatibility-preserving activation; the server-first Hello cannot advertise 21 without stranding existing v20 clients before AttachRequest. v15 = CompletionPopup + StatusFacts.message; v16 = ThemeFacts; v17 = FontFacts; v18 = StatuslineSegments; v19 = the vterm terminal family; v20 = semantic SessionBootstrapRequest plus appended InitialTargetResult; v21 reserves the panel frame/event family. New wire surface ⇒ bump + both-frontends support + acceptance. An APPENDED variant must be guarded by a byte pin on the PREVIOUS final variant — its own round-trip cannot detect a discriminant shift.

Fake LSP (src/bin/pmacs_fake_lsp.rs) modes: fullonly, rangeonly, rangeonly16 (UTF-16 + fail-closed bounds validation), sighelp. Use these for capability-matrix tests, not real servers.

5. Hard-won ops lessons

• A gate summary assembled through a pipe can report success over a failure. cmd | tail -2 returns tail's exit status, not cmd's — in fish and bash alike — so a chain of cargo test ... | tail -2 && cargo test ... | tail -2 && echo "ALL GATES CLEAN" prints the clean line even when a suite failed. This is not carelessness that closer reading would catch: the failure is structurally invisible in the summary the PR then cites. It happened while gating the silent-skip lane, and a pmacs-gpu failure was reported as clean.

  Either check $pipestatus[1] in fish (${PIPESTATUS[0]} in bash), or — better — redirect each gate to a file and read the file afterwards, which also preserves the full log this section already asks you to keep. Same family as the skip-reports-ok lesson below and the double-invocation traps: the thing that summarizes a gate must not be able to lose the gate's verdict.

• A reproduction is a measurement, and needs its own positive control. The basedpyright-hang lane wrote four reproductions that passed against the unfixed tree, each vacuous for a different reason: the child exited before the join; the child never read stdin at all; the child's stdin was silently rebound to /dev/null (POSIX XCU §2.9.3 assigns /dev/null to an asynchronous list's stdin when job control is off, so sh -c 'cat & exit 0' EOFs instantly); and then the repair for that was also wrong — the rule applies before explicit redirections, so <&0 duplicates /dev/null onto itself. bash skips the default when a stdin redirect is present, dash does not, so <&0 passed locally and failed in CI. The shipped test uses setsid --fork, removing the shell from the reproduction entirely. Every one of the four looked obviously right when written, and the fourth was verified locally before it failed. Note what a narrower rule would have missed: "check the child is still alive" catches only the first. Only the general form catches all four — and the ones nobody has invented yet. Note also which mechanism caught the fourth: not a reviewer, but the control itself, failing loudly in CI and naming its own cause. So: assert the precondition your reproduction depends on, in the test, before exercising the thing under test. In teardown_closes_stdin_before_joining_readers that is two controls (the recorded child has exited; both readers are still blocked in read), each with a failure message naming what its absence means — and a /bin/sh that is bash locally and dash in CI is exactly the sort of divergence no amount of local verification reaches. This is the same rule that produced #192's bite positive control and #194's re-read-the-artifact lesson, stated at full generality: a measurement you have not controlled is a claim, not evidence.

• A Drop body runs before its fields, whatever the declaration order. Cost a multi-week misattribution: RuntimeHandles::drop joined its reader threads in the drop body, while the stdin sink it needed to close first sat in a field — reachable only after that body returned. The child never got EOF, never exited, and kept the output pipe the readers were blocked on, so teardown hung forever. Reordering the struct's fields cannot fix this shape; the operation has to move into the body. Generally: if a Drop body waits on anything, check what the waited-on party needs that only a field drop will release. Corollary from the same investigation — cancel-flag style wake-outs only work where the thread actually polls them; a thread blocked in a raw read never sees one, so a flag next to a blocking syscall is documentation, not a mechanism.

• A test that skips on a missing precondition reports ok, and a gate log cannot tell that apart from a pass. vterm_stage3_acceptance::a37 — the only acceptance driving a real daemon, a real PTY and a real wgpu render together — derives pmacs-gpu from CARGO_BIN_EXE_pmacs and, when that binary is absent from the target directory, prints a skip and returns. A fresh worktree reports the suite 9/9 in 0.17 s having never run it; a real run takes ~4 s. PMACS_REQUIRE_GPU=1 is what promotes the skip to a failure, and the standing gate list applies that flag to cargo test -p pmacs-gpu, a different package. Two habits follow: build the workspace before believing any suite that reaches for a sibling binary, and judge such a suite by its elapsed time, not its verdict.

• Before attributing a red test to your branch, run it on the merge base. a37 failed on the #173 branch, which looked like a regression; it failed identically on the PR's own base and on two intermediate commits, and had passed on that same base twenty minutes earlier. The variable was machine load from a second agent compiling continuously. Load-sensitive tests make both verdicts uninformative in isolation, so the base-commit run is the cheapest way to tell a regression from weather — and it is much cheaper than the bisect it replaces.

• A daemon-side fix is not deployed until the daemon is restarted from a tree that contains it. #166's reporter rebuilt and saw no change: the running daemon had been started from a shared checkout still on a pre-fix branch, and pmacs --gpu attaches to whatever process already owns the socket. Rebuilding a binary does nothing to a running process. When validating a daemon-side fix by hand, check the running process's binary path and start time against the tree you think you fixed — ps -eo pid,lstart,args | grep '[p]macs --daemon' — before concluding the fix failed.

• Two operations that must be alternatives are not made alternatives by being adjacent. The dispatcher applied its grid and semantic terminal-layout syncs to every attached frontend; a semantic session satisfies both conditions, so its PTY was resized twice per tick forever and the child took a SIGWINCH storm that made a GPU terminal untypable while output still flowed. Each arm had a correct old_size == size idempotence guard — individually sound, jointly useless, because each saw only the size the other had just written. Write mutually exclusive per-frontend-kind work as one if/else keyed on the same fact session establishment uses, and extract the loop body so a test can drive the real thing.

• Bite against every pre-image the fix could plausibly have taken, not just main. For the same defect, the obvious one-line guard (skip the grid arm for semantic frontends) does fix the storm — and silently introduces a controller leak, because that arm was also the only per-tick controller-liveness release a semantic frontend got. A single revert would have scored the fix complete. The pin that catches it (acc 6) deliberately passes on main and fails only against the naive guard: today's defect supplies the release by the accident of running an arm it should not.

• A quiet child is an instrument. A frame storm is invisible against a fixture that legitimately emits hundreds of frames, and an assertion like frames >= 2 cannot see one. The same applies to geometry: a "did a frame at the new width arrive" readout is satisfied by a geometry oscillating through that width. Assert upper bounds over a fixed window against a child that produces nothing, and let the child self-report the signal you care about (a SIGWINCH trap printing a fresh distinct breadcrumb per signal — repeated identical markers paint nothing, because cell::diff skips already-matching cells).

• TerminalMode::Raw makes sh-based input fixtures useless. There is no ICRNL, so Enter delivers CR and a read -r loop waits forever for a LF that never comes — the test then "proves" input never arrived. Use exec cat, which copies stdin to stdout byte by byte. It is also the right echo instrument for the opposite reason people assume: termios ECHO is off in raw mode, so nothing double-echoes and one keystroke yields exactly one cell.

• Draining the event stream to learn a pid also TICKS, and a tick reaps. #176's observing_the_leader_does_not_consume_the_exit_event failed under load with "process ProcessId(26) is not running": its helper drained for Started to read the pid, drain_until ticks while it drains, and a tick can observe an immediately-exiting child and move the record out of Running — after which signal never reaches the code under test at all. It passed standalone only because the drain returned on Started before poll_one saw the exit. Read the pid straight from the supervisor record, which does not tick, and fail fast if the record has left Running. Verified load-bearing under matched load: 0/15 failures with all 16 cores saturated versus 1/10 for the ticking helper. The general rule: an observation helper that advances the system is not an observation.

• A wait predicate that is WEAKER than the assertion it guards is a race, on every platform that happens to lose it. #174: the m4 config sink test waited for contains("probe") and then asserted "probe":true — six bytes further on. The sink is JSONL written by a separate process, so the test could read a half-written line; Linux won that race reliably and macOS/lua54 did not, reporting the truncated {"rust":{"probe":. Any "wait until the file mentions X, then assert Y about the file" shape races whenever Y is stricter than X. The fix is to wait for the exact unit the assertion reads — here a trailing newline, true only once a whole writeln! record has landed, and still correct if the payload's field order or spelling changes. Two things generalize beyond the fix:

  • A race you cannot reproduce can still be bitten at one remove. The failure needs a scheduler outcome Linux does not produce, so no local run falsifies it. But pump_async asserts on its deadline, so replacing the predicate with an unsatisfiable one proves the wait is load-bearing rather than decorative — and restoring the old predicate, which still passes locally, proves a green local run cannot distinguish the two. Bite what you can reach and say plainly which claim rests on structure instead of evidence.
  • The obvious fix is sometimes worse. The sibling m4_26 has the same weak shape and was deliberately left alone: waiting for the expected value would convert a genuine rootUri regression — what its assert_ne!s exist to catch — into a five-second timeout with a misleading "server didn't initialize?" message, trading a precise assertion diff for a vague hang. Closing it properly needs a record terminator in the fake server first.

• Proving a child has exited is harder than it looks on this codebase. A fixed sleep is not proof; nix's waitid is unavailable on macOS; and libc::waitid needs unsafe, which #![forbid(unsafe_code)] rules out. What works is driving the production diagnostic in a bounded loop until it observes the exit. Relatedly, #176's round-1 review replaced every substring assertion with exact message equality built from the kernel-assigned pid — the substring forms would have accepted a hardcoded target or a wrong exit code.

• The checkout may be shared with the user. Check git status for foreign uncommitted work before any stash/checkout/branch surgery; never assume dirty files are yours. (Their uncommitted fix was nearly orphaned once.) A clean status goes stale within minutes when two lanes are active — for parallel work, git worktree add a sibling directory off main instead of switching the shared checkout.

• Never git stash in this repo. The stash namespace is REPO-GLOBAL — one list shared across every worktree and with the user; a scripted push/pop can pop a human's years-old stash into your tree (happened during #111: a failed stash push chained into stash pop, which grabbed the user's PR-#17-era entry). For run-tests-against-an-old-version swaps, use scripts/bite — a trap-guarded one-file swap over read-only git show, with a two-sided verdict (the tests must PASS now and FAIL against the old version), making bite-verification machine-checkable.

• scripts/bite is only as good as its positive control, and it had none until it was given one. Before that it ran only the swapped tree, so it could not tell "my fix is load-bearing" from "my test is broken": a test that fails everywhere made the swapped run fail, and a failing swapped run was the only thing checked, so it printed bite: OK and certified nothing. It now asserts the named tests pass and that at least one actually ran (a filter matching nothing exits 0, so passing alone is not enough), exiting 3 as NO CONTROL otherwise. It also distinguishes OK (assertion) from OK (COMPILE) — an old file that does not build against the current tree is a much weaker result, because the tests may never have run at all. Read which one it printed.

• A fix must be COMMITTED before it is bitten — but not for the reason previously recorded here. This file used to say scripts/bite "restores by git checkout --, which reverts the file to HEAD", and that a review round's fixes were wiped that way during #165. That mechanism description is false and was verified false: the script copies the file to a mktemp path before the swap and restores from that copy, under an EXIT INT TERM trap, so uncommitted work in the bitten file survives. It has never touched git state beyond a read-only git show. The rule still stands on its own merits — gate results must describe the pushed tree, and a cargo fmt after a commit splits worktree from branch — but do not repeat the destroys-your-work claim, which will push the next reader toward git stash to protect themselves, straight into the repo-global trap above. The #165 incident itself is now unexplained, and that is recorded rather than papered over: work really was lost, but not by the mechanism this file blamed. A SIGKILL bypasses the trap and would leave the swapped file in place, which is one candidate; so is a stash collision, given the same round. Do not invent a mechanism to close the gap — an unexplained incident is safer than a confident wrong cause, which is what produced this correction. Corollary for a NEW file: the swap-over-git show mode does not apply at all, so its claims must be bitten by hand-editing.

• A CONFLICTING PR silently runs no CI at all. GitHub builds pull_request workflow runs against the PR's merge ref, which it does not create while the branch conflicts with its base. So pushes land, the branch updates, no run is ever queued, and nothing reports the absence — the checks list simply keeps showing the last successful run, which reads as current. Three pushes to #165 produced zero CI before the cause was found, and gh pr checks returns nothing usable here. On any lane that lives through a moving main, check gh pr view <N> --json mergeable,mergeStateStatus,headRefOid and confirm a run exists for the current head sha, not merely that a recent run was green.

• Stacked PRs: retarget the child to main BEFORE merging the parent — GitHub auto-closes a PR whose base branch is deleted and cannot reopen it (#104 → re-opened as #105).

• Frozen reviewed PRs do not absorb moving overlapping work. For #135 and #137, the approved/frozen #137 landed first; the larger #135 lane then merged canonical main, retained its review anchors, and reran every gate. Derive that integration surface from git diff <base>..main, not the other PR's file list — concurrent landed work added an overlap the original two-PR comparison missed.

• Scripted edits (sed/python) in files with repeated similar blocks (src/lsp.rs JSON builders): anchor on a unique line or you will silently edit the wrong block. This produced a vacuously-passing test and cost an hour.

• Acceptance fixtures that open .rs/.py files must empty pmacs.lsp.config first — the after-load hook spawns real servers (rust/python/c have default configs). Language detection (grammars + pmacs.lsp.filetypes) is unaffected.

• Test scratch buffers have no path ⇒ no language; use tempdir files when language matters.

• Dual-purpose session state is a reset-contract trap (#120 rounds 2–5): last_status doubled as the peer emission baseline AND the stale-diag count freeze, so resetting baselines on BufferSnapshot zeroed mid-edit counts. Knowledge about a buffer belongs in shared stores (DiagnosticStore severity totals), never in per-session baselines; and any daemon-side reset needs its frontend mirror audited in the same round (the GPU snapshot arm missed search/menu/status the first time).

• Tab width is a rendering semantic, NOT a config gap. The implementation on tab-width-parity fixes the width at the TUI's established 8 columns, shares that constant through pmacs-protocol, and expands tabs only in each display projection. Defining editor.tab-width could not have fixed the GPU: source text and semantic spans stay byte-addressed while cosmic-text needs projected spaces plus an inverse hit/caret map. A future configurable width would require a buffer-effective frontend fact and cache invalidation; do not re-plan it as a scalar config-only change.

• A test that never runs passes. Two #127 review-round tests passed vacuously at first: pmacs.editor.save() is the RAW save, while buffer.before-save fires inside the buffer.save COMMAND (builtin/commands/default.lua), and save() no-ops on an unmodified buffer — so a fixture that opens a file and saves it asserts on bytes nothing rewrote. Dirty the buffer with a real edit and go through pmacs.command.invoke("buffer.save"). Caught only because the other case failed and the cause was chased instead of the assertion adjusted.

• A message that ALIGNS state cannot be gated on the state it names. FrontendEvent::Viewport both declares a byte range and switches the frontend's window to the buffer it names. Gating the vterm v19 dual declaration on "is the DECLARED buffer a terminal" therefore left a stale in-flight document viewport free to drag a frontend straight back off a terminal a command had just opened — the window oscillated, the terminal declaration was refused every time, and no frame ever arrived. Nothing errored. The gate has to key on the authenticated source's ACTIVE buffer. Generalizes: when two messages declare competing views of "what am I showing", the arbiter is the daemon's own state, never the claim inside either message.

• A pass that sets a mode flag must clear it on EVERY exit. The semantic producer's terminal pass returned early via ? when no declaration existed, leaving terminal_active set — and the daemon uses that flag to suppress CursorByte and the presence sweep, so a frontend that went back to a document silently lost both. Caught by an acceptance assertion, not by any type.

• Sub-crate acceptance needs a real seam, not a fixture. pmacs-gpu depends only on pmacs-protocol, so "real daemon + real PTY + real wgpu in one path" could not be an in-crate test. Generalizing attach::connect's reader sink (connect_with_sink) and adding --headless-probe gave the acceptance the REAL handshake, outbox, writer, and render_to_view — which is the whole point; a decoded-message fixture would have proved none of the three fit together. The probe found two real defects the in-process tests did not.

• Real-grid acceptance must budget for macOS startup and path width. A 100 ms first-Hello timeout failed under loaded macOS CI; use the normal five-second handshake window, then short polling reads. An 80-column split also clipped a custom statusline segment after macOS's long /var/folders/... temp path while passing on Linux; size the grid for the longest supported fixture path (the mode-system test uses 160 columns per split).

• A provisional session that fails mid-bootstrap must actually close its socket, not just drop its handle. #148's dispatcher-side target-failure paths wrote InitialTargetResult::Failed and dropped the write-half UnixStream clone, but a clone shares the underlying FD — the per-attach reader thread stayed alive with no installed session state. A client that kept the socket open past Failed and sent any ordinary event hit an .expect reachable only through the new failure path and panicked the whole daemon. Fix: shutdown(Shutdown::Both) on every dispatcher-side failure path, plus a defense-in-depth session-registry membership check before any FrontendEvent touches render/size/editor state. Generalizes: when a new failure path can leave a handle installed without its owning session, dropping a handle is not the same as tearing down the connection.

• A guard with no production caller passes every direct-call test. #155 round 1: EditorCore::try_split_active implemented the side-window split refusal, but pmacs.window.split_horizontal / split_vertical — and therefore C-x 2 / C-x 3 — still called plain split_active. The acceptance test called the core method directly, so reverting the guard entirely would have left every test green. Same shape as folding #142 round 2. Assert through the outermost user-reachable seam (try_exec(&s, "pmacs.window.split_horizontal()")), then falsify by revert. When the test shares a file with the code it pins, scripts/bite cannot swap it — break the production line by hand and git checkout --.

• A geometric readout is not a state predicate. TerminalViewStatus::at_bottom is defined as scroll_offset == 0 — "the viewport currently reaches the tail", not "this view follows the tail". A still-anchored view satisfies it whenever it happens to be tall enough, so asserting it could not detect that Q#BP7's growth re-arm had never been implemented (#155 round 2): the next rows the child printed pushed the anchored view back into history. Pinning following requires advancing the world — feed more child output through a filesystem gate — and asserting the view came along. Related: scroll_offset is viewport-relative, so "unchanged across a height change" is vacuous or wrong; the invariant is the frozen ANCHOR.

• A PTY in the default mode does not translate LF to CRLF. An echo-driven test fixture staircases rightward, and past the viewport width every row clips to blanks — so assert_eq!(top_before, top_after) compares "" == "" and passes for any regression (#155 round 2). Emit printf '...\r\n', and guard text comparisons with assert!(!observed.is_empty()) the same way the panel daemon pin guards on !panel_hidden.

• Widening an ambient resolver into a scoped one can make a total function partial. #155 round 2 resolved both arms of pmacs.window.buffer() through the acting frontend "for uniformity". acting_frontend follows the interactive origin, which can name a frontend with no registered view (a bare dispatch_key from an unattached peer), so the no-argument arm began raising instead of answering. No runtime caller pcalls it, so killring, syntax, autosave, pair, indent and comment silently dropped operations — kill_ring_acceptance went 30/30 to 25/5 on every CI platform. The ambient resolver's fallback is what makes it total; keep it, and document that as deliberate. Uniformity is not free when the paths have different totality.

• An upgrade decision must be tracked independently of the outcome that triggered it. #148 published a target's fresh BufferSnapshot to existing grid replicas only when the buffer was newly_loaded || newly_created — but a target can dedup onto an already-existing, not-yet-CRDT-backed buffer (e.g. one a startup hook created via find_or_open and never activated), silently upgrading it without telling pre-attached replicas. The later F29 lazy-upgrade sweep then saw an already-backed buffer and never broadcast it, permanently stranding those replicas on v0.1 round-trip for that buffer. Fix: have the upgrade helper report whether it performed the upgrade, and OR that into the publish decision rather than inferring it from the caller's own load/create branch.

6. Named deferrals (the standing backlog, consolidated)

Editing: word kills (M-d/M-BS — need bytes-returning deleters + prepend-on-backward append), C-SPC set-mark, C-u C-y / C-M-w, kill-ring browser + persistence, clipboard watching, block comments + mid-line comment spans, comment-dwim append-at-EOL, per-language comment padding. Pairing (framing "Deferred"): wrap-region on opener, pair-aware backspace, RET-inside-pair closer-on-own-line, in-string/in-comment inhibit (needs node-at-byte pmacs.parse), undo amalgamation (pair = one step), balance-aware quotes (the per-buffer toggle SHIPPED in #127 as editing.auto-pair). Editops deferrals (full list in its framing): recenter (blocked on viewport facts — the GPU never consumes daemon view_top), Unicode case/word classes, region-spanning move/duplicate, locale collation for sort-lines, ensure-final-newline on save. Substrate: buffer-aware edit epoch (after-edit currently compares the ACTIVE buffer only), wire provenance for CRDT self-insert classification, Lua intercept probe, completion.lua still on the old cursor-delta heuristic (migrate to this_command), the TUI's nonempty-selection optimistic type-over gate, generated-buffer search invalidation, cross-peer chronological undo arbitration (mixed source/daemon history; pinned by auto-pairing acceptance), origin-pinned buffer.after-edit fan-out (a context-switching intercept changes what later callbacks — LSP, completion — observe). LSP/persistence: hidden-buffer LSP attach, daemon desktop-restore, the warning half of external-change detection (verify-visited-file- modtime). Config registry (SHIPPED #127; these are its own named deferrals): persistence of settings and the custom-file split-brain question, M-x list-settings as a listview panel, a settings completion source for the minibuffer (minibuffer.read's source is a fixed Rust-side vocabulary), table-valued settings (so pmacs.lsp.config, pmacs.pair.sets, pmacs.comment.strings and the pmacs.parse.* write-through proxies stay raw Lua), migrating the remaining scalar setters (async_config ×2, killring.max, the enable booleans) and pmacs.gpu.set_font, pending-set staging for names defined after init.lua runs, and a scope = "global" define flag — set_local is currently accepted for autosave.interval-ms, where a per-buffer value is meaningless. Tab width is NOT a config gap — see §5. Mode system (SHIPPED #129): minor modes, buffer.after-mode-change, mode-scoped settings, describe-mode, and persistence of explicit major-mode overrides/clears across sessions. Modeline detection (SHIPPED #132): bounded first/last-line Emacs -*- and Vim ft=/filetype= parsing, explicit-over-inferred precedence, alias normalization, and shared fresh-load language pinning for syntax/highlight/LSP startup. Highlight/detection (from the #114–#118 side-quest + injections #122): locals-query processing SHIPPED #134; remaining injection follow-ups now that the engine landed (#122) — injection.combined (many matches → one shared parse; PHP-in-HTML, some comment schemes), child-tree incrementality + range-scoped layer rebuild (child layers cold-reparse on every settle today), injectable runtime/Lua-registered languages (v1 resolves only against BUILTIN_LANGUAGES), and the next injection consumers gated on new grammars — HTML/CSS/GraphQL/SQL (<script>/<style>, JS/TS template literals, doc-comment code); modeline detection as a 5th layer (-*- mode: … -*- / # vim: ft=…) SHIPPED #132; byte-accurate multibyte cursor placement in move_active_cursor_to (still steps one codepoint per LSP byte column). A full Jupyter .ipynb setup (reader → editable → kernel execution) now has its JSON grammar prerequisite, but remains a real arc, not a one-shot. GPU: auto-reconnect after daemon restart, splits/multi-buffer, gutter riders (whitespace guides, folding, git markers). Themes (full list in theme-faces framing rev 9 "Deferred (named)"): popup/menu/dropdown bg + selected-row faces, ui.background / ui.caret, ui.modeline.inactive, minimap chrome, peer-cursor palette (+ui.selection for peer rects), ui.inlay_hint (needs the epoch treatment on its producer), wire alpha, Indexed palette unification, named-theme registry / light theme / persistence (the registry exists now, #127; theme persistence still waits on settings persistence), grid-vs-wire default_style asymmetry, mask widening (gutter bg, wash glyph recolor, statusline bg echo surface, chrome bold/italic/underline re-shaping). Housekeeping: F-016 lua_bindings/mod.rs split paused mid-way (tranches 0–2 landed, ~5–8 PRs left; see docs/lua-bindings-split-framing.md). Full cross-cutting index of the non-themes backlog (this list + every framing doc's Deferred section + a code sweep, themes excluded, with a prioritization north star): docs/side-quest-backlog.md.

7. Machine-local facts (desktop) that do NOT travel

Three untracked files live only on the desktop working tree and are deliberately never committed: docs/pmacs-gpu-editing-perf-handoff.md, docs/session-5-stale-styling-handover.md, python_experiment.md. Don't expect them in a clone; on the desktop, never delete them.

8. Update protocol for this file

When a PR merges, an arc opens/closes, or a decision lands: edit the snapshot (§1), append lessons (§5) and deferrals (§6) as they arise, bump the date line at the top, and commit — usually riding the same PR as the work. Keep durable architecture here; put branch hashes, machine-local tools, incomplete verification, and recovery commands in docs/active-work.md. This is a briefing, not a log: prune sections that stop being true.