docs(stage3): the fallout census — 37 failures, and a transitive adopter

Branch-plan step 1, whose whole point is that it precedes the flip. The
throwaway edit is NOT in this commit; only the measurement survives it.

A CENSUS THAT STOPS AT THE FIRST FAILING BINARY IS NOT A CENSUS. The
first sweep reported 2 failures in 1 suite and looked comfortingly
small — `cargo test` halts after a failing test binary, so everything
alphabetically past bottom_panel_stage1_acceptance never ran. With
--no-fail-fast the real figure is 37 failures across 5 suites. Any
re-measurement must pass that flag or under-report by an order of
magnitude, which is the same silent-success shape this arc keeps
finding.

M4_ACCEPTANCE WAS PREDICTED BY NOBODY — not the parent framing, not
Q#BP12's adopter table, not revision 1. Its two failures are the LSP
hover and outline panels, which are LISTVIEW CONSUMERS, so flipping
listview's default reaches the LSP suite transitively. Q#BP12's four
rows are the DIRECT population; the real one is everything built on
listview. That is the intended behaviour, but the map has to say so or
the next listview-based feature inherits a default nobody documented.

THE PROPORTIONS INVERT THE OBVIOUS READING. compile_mode has the most
failures (17) and the least placement content — process-lifecycle and
styling tests that merely use compile and now find its output
elsewhere. listview_acceptance has fewer (13) but loses THREE QUARTERS
of its suite, and its failures are placement in substance.

Classification decided per test, not per suite, because two
neighbouring compile tests land on opposite sides: acc15
(RET-visits-error, jump-back) is placement — Q#BP12 explicitly requires
panel → RET source → M-, back to the still-present panel with the
document window intact — while acc16 (n/p walk within compile output)
genuinely needs the compilation buffer selected and takes an explicit
display = "current". A sweep classifying per suite would have got both
wrong.

Both M4 failures are placement-subject: outline_panel_opens_visits_and_
restores is almost a direct realization of criterion 58 (open → visit →
jump-back → quit), and hover_doc_panel keeps the omitted default while
asserting the new placement plus its existing content and quit
guarantees. Neither takes display = "current".

Tree verified clean after revert: the three default-resolution branches
are unchanged on disk.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

docs/bottom-panel-stage3-framing.md

@@ -1,7 +1,14 @@
 # Framing — Bottom panel Stage 3: the adopter default flip
 
-**Revision 2.** Status: **approved with amendments** (revision 1 → 2
-records them). Scouted against `githubsucks/main` @ `000b6cd` (v1.1.0).
+**Revision 3.** Status: **approved; branch-plan step 1 (the fallout
+census) is complete and recorded in §1.6b–c.** Branch
+`bottom-panel-stage3`, based on `githubsucks/main` @ `21de0b2`.
+
+**Revision 2 → 3** adds the measurement and its classification. Two
+findings changed the plan rather than confirming it: the census needs
+`--no-fail-fast` or it under-reports by an order of magnitude, and
+**`m4_acceptance` is a transitive adopter via listview that no table
+named**.
 
 **Revision 1 → 2**, all from review and all verified rather than
 accepted:
@@ -192,9 +199,8 @@ fallback is invisible from the adopter's side.
 - **Nothing has been implemented or measured.** Unlike the distribution
   lane, there is no artifact to inspect; the evidence is the existing
   suites' behaviour before and after.
-- **The blast radius on existing acceptance suites is partly known
-  now** — see §1.6a for the two named cases. The total is still
-  unmeasured. Stage 1
+- ~~The blast radius on existing acceptance suites is unmeasured.~~
+  **MEASURED — see §1.6b: 37 failures across 5 suites.** Stage 1
   shipped the mechanism opt-in precisely so existing suites kept their
   meaning. Flipping the default changes where output lands for every
   suite that exercises listview, compile or terminal **without** passing
@@ -234,6 +240,79 @@ to make a suite green converts a behavioural change into an invisible
 one, which is the failure this stage's inverted ordering exists to
 avoid.
 
+### 1.6b The fallout census — MEASURED, and it found an adopter nobody named
+
+Taken as branch-plan step 1: record a baseline, apply the three-site
+flip as a throwaway edit, sweep, revert. The flip is **not** in the
+tree; only this table survives it.
+
+**A census that stops at the first failing binary is not a census.**
+The first sweep reported **2 failures in 1 suite** and looked
+comfortingly small — `cargo test` halts after a failing test binary, so
+everything alphabetically past `bottom_panel_stage1_acceptance` never
+ran. With `--no-fail-fast` the real figure is **37 failures across 5
+suites**. Any future re-measurement must pass that flag or it will
+under-report by an order of magnitude, in the same shape as this arc's
+other silent-success traps.
+
+| suite | base → flipped | failures | share of suite |
+|---|---|---:|---:|
+| `listview_acceptance` | 17 → 4 | **13** | **76%** |
+| `compile_mode_acceptance` | 72 → 55 | **17** | 24% |
+| `vterm_stage2_acceptance` | 6 → 3 | **3** | 50% |
+| `bottom_panel_stage1_acceptance` | 46 → 44 | **2** | 4% |
+| `m4_acceptance` | 149 → 147 | **2** | 1% |
+| | | **37** | |
+
+**`m4_acceptance` was predicted by nobody** — not the parent framing,
+not Q#BP12's adopter table, not revision 1 of this document. Its two
+failures are `hover_doc_panel_shows_full_contents_via_binding` and
+`outline_panel_opens_visits_and_restores`: **the LSP panels are
+listview consumers**, so flipping listview's default reaches the LSP
+suite transitively.
+
+This materially improves the adopter map. Q#BP12 lists four rows
+(listview, compile, terminal, DAP) as though they were the population.
+They are the *direct* population; **the real one includes everything
+built on listview**, and the LSP hover/outline panels are the proof.
+Anything added on listview later inherits the panel default without
+appearing in any table — which is the intended behaviour, but only if
+the map says so.
+
+**The proportions invert the obvious reading.** `compile_mode` has the
+most failures and the least placement content: `acc01_spawn_streams…`,
+`acc05_kill_reaps_backgrounded_descendant`,
+`acc21_kill_produces_signaled_marker` and the `r1f*`/`r5f*`/`r6f*` group
+are process-lifecycle and styling tests that merely *use* compile and
+now find its output elsewhere. `listview_acceptance` has fewer failures
+but loses **three quarters of its suite**, and its failures
+(`open_seats_cursor_and_ret_visits_the_row`, `panel_rejects_typing`,
+`dispatch_idle_is_false_while_a_panel_is_focused`) are placement in
+substance.
+
+### 1.6c Classification, decided
+
+Applying §1.6a's rule to the measured set. **Placement-subject tests
+assert the NEW default; only genuine document-window setups opt out.**
+
+| test | classification |
+|---|---|
+| `bottom_panel_stage1::acc19` | **placement** — needs a new way to seed a document window (§1.6a) |
+| `bottom_panel_stage1::acc19b` | **placement** — subject survives; mechanism may not (Q#S3-3) |
+| `m4::outline_panel_opens_visits_and_restores` | **placement** — *almost a direct realization of criterion 58*: open → visit → jump-back → quit. Assert the panel/document split |
+| `m4::hover_doc_panel_shows_full_contents_via_binding` | **placement** — a listview panel lifecycle test. Keep the omitted default; assert the new placement **plus** its existing content and quit guarantees |
+| `compile::acc15_ret_visits_error_and_jump_back_returns` | **placement** — Q#BP12 explicitly requires compilation panel → RET source → `M-,` back to the still-present panel with the document window intact |
+| `compile::acc16_n_p_walk_error_lines_without_wrap` | **opt out**, explicit `display = "current"` — its subject is cursor navigation *within* compile output, which genuinely needs the compilation buffer selected |
+| `listview_acceptance` ×13 | **placement**, predominantly — assert the new default |
+| remaining `compile_mode` ×15 | **incidental** — process lifecycle and styling; opt out only where the setup needs the document window |
+| `vterm_stage2` ×3 | **to classify at implementation** — terminal's `select = true` makes these likelier placement than incidental |
+
+The `acc15` / `acc16` split is the one worth remembering: **two
+neighbouring tests in the same suite land on opposite sides**, because
+one is about where output goes and the other is about moving within it.
+A sweep that classified per *suite* rather than per *test* would have
+got both wrong.
+
 ## 2. Questions
 
 - **Q#S3-1 — DECIDED: unify NARROWLY.** A shared