docs: destination-capture revision 4 --- pin the commit_to call shape

Revisions 2 and 3 said "the profile is declared at commit_to" and never
said how. That is not a detail. The binding accepts exactly (dest,
body) today, so without a specified form #227 has no stable API to
adopt against, and the promise that existing callers keep their
semantics was a hope rather than a contract.

Q#DC-5: commit_to(dest, body [, profile]). An optional TRAILING string,
typed Option<String>, so there is no arity sniffing and no
table-or-function dispatch on argument 2 --- the existing binding chose
Value over AnyUserData specifically to keep its error message reachable
and naming the rule, and a polymorphic second argument would undo that.

Trailing reads badly after a long inline closure, but that is not the
call shape in use: dired defines a named local commit at dired.lua:670
and calls commit_to(opts.dest, commit) at :717. Verified, not assumed.
Against a named body the trailing profile reads fine.

The value set is CLOSED --- document and panel, exactly Q#DC-2 two
profiles. A third is a decision, not a spelling.

Omitted means document, and that is the load-bearing part: every
existing two-argument call keeps all four preflight checks by
definition of the signature, so journey_acceptance passing untouched
follows from the API shape rather than from care.

An unrecognized profile is an ERROR naming the accepted values, not a
silent fallback to document. A fallback would hand a caller stricter or
looser checks than it asked for, which is the failure the whole
parameterization exists to prevent. Its witness asserts the legacy
two-argument form through a check the panel profile OMITS --- a
stale-buffer refusal --- because asserting merely that it does not
error would pass on a call silently downgraded to panel, which is the
regression that would quietly void Journey Stage 1a guarantees.

Git mapping settled here rather than rediscovered during adoption:
*git-status* takes panel, *git-diff* takes document.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016bqGA6s9tTUFzYpbeW3tai
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Levi Neuwirth 2026-08-09 16:18:00 +02:00
parent 6b8e07c730
commit 1b4046b624
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2 changed files with 84 additions and 4 deletions

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@ -275,8 +275,21 @@ from #171 and #215.
authoritative tip** — the ref, not a SHA. Recover with
`git fetch githubsucks && git checkout destination-capture`.
- **Framing `docs/destination-capture-framing.md`, revision 3**, in
review. Revision 2 took three findings: Q#DC-2's parameterization was
- **Framing `docs/destination-capture-framing.md`, revision 4**, in
review.
- **The public API #227 adopts against (Q#DC-5), pinned so it is a
contract rather than an intention:**
`pmacs.window.commit_to(dest, body [, profile])`. Profile is an
optional trailing string from a **closed** set — `"document"` and
`"panel"`. **Omitted means `"document"`**, so every existing
two-argument caller keeps all four preflight checks *by definition of
the signature*, which is what makes `journey_acceptance` passing
untouched a consequence rather than a hope. An unrecognized or
non-string profile **errors**, naming the accepted values — a silent
fallback would hand a caller different checks than it asked for,
which is the exact failure the parameterization exists to prevent.
Git's mapping is settled here too: `*git-status*` → panel,
`*git-diff*` → document. Revision 2 took three findings: Q#DC-2's parameterization was
incomplete (a panel depends on **none** of checks 24, not just check
3, so the question now carries a full preflight matrix with every
omission testable); `tests/journey_acceptance.rs` joins dired as a

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@ -1,8 +1,19 @@
# A destination capture any async continuation can use
**Status: framing pass, revision 3. Pre-implementation. Awaiting
**Status: framing pass, revision 4. Pre-implementation. Awaiting
approval.**
**Revision 4 specifies the call shape the last two revisions kept
referring to without defining.** "The profile is declared at
`commit_to`" named no signature, no value set, no invalid-profile
behaviour, and nothing about the existing two-argument callers — so
#227 had no stable API to adopt and the Journey preservation promise
rested on care rather than contract. Q#DC-5 fixes that:
`commit_to(dest, body [, profile])`, a **closed** two-value set,
**omitted means `"document"`** so every existing call keeps all four
preflight checks by definition, and an unrecognized profile **errors**
rather than falling back.
**Revision 3 decides Q#DC-4, which revision 2 left contradicting
Q#DC-2 — on the primary panel API.** Q#DC-2 concluded a panel needs
only a live frontend; Q#DC-4 still returned `nil` without a document
@ -250,6 +261,53 @@ buffer kind.
The Q#JR14 doc comments should keep their references intact; a rename
that orphans the rationale is worse than a slightly stale name.
### Q#DC-5 — the exact Lua call shape for the profile **(new in rev 4)**
Revisions 2 and 3 said "the profile is declared at `commit_to`" and
never said **how**. That is not a detail: today's binding accepts
exactly `(dest, body)` (`window_panel.rs:453-456`), so without a
specified form #227 has no stable API to adopt against, and the
promise that existing callers keep their semantics is a hope rather
than a contract.
**The signature:**
```lua
pmacs.window.commit_to(dest, body) -- document profile
pmacs.window.commit_to(dest, body, "panel") -- panel profile
```
- **`profile` is an OPTIONAL THIRD argument**, a string, typed
`Option<String>` at the binding. No arity sniffing, no
table-or-function dispatch on argument 2 — the existing binding
chose `Value` over `AnyUserData` specifically so its error message
would stay *reachable* and name the rule, and a polymorphic second
argument would undo that.
- **Trailing, and readable in practice.** A profile after a long inline
closure would read badly, but that is not the call shape in use:
dired defines `local function commit() … end` and calls
`commit_to(opts.dest, commit)` (`builtin/runtime/dired.lua:670,717`).
Against a named body, `commit_to(dest, commit, "panel")` reads fine.
- **The value set is CLOSED: `"document"` and `"panel"`.** Exactly the
two profiles in Q#DC-2's matrix. Not an open string namespace — a
third profile is a decision, not a spelling.
- **Omitted means `"document"`.** This is the load-bearing part: every
existing `commit_to(dest, fn)` call keeps **all four** preflight
checks, unchanged, by definition of the signature. `journey_acceptance`
passing untouched (§7) then follows from the API shape rather than
from care.
- **An unrecognized profile is an ERROR**, naming the accepted values —
**not** a silent fall back to `"document"`. A fallback would hand a
caller stricter or looser checks than it asked for, which is the
failure mode the whole parameterization exists to prevent. A
non-string profile errors the same way.
**Which profile each of git's continuations takes**, so #227's adoption
is decided here rather than rediscovered: `*git-status*` → **panel**
(it lands in the bottom panel, `listview.lua:550`); `*git-diff*`
**document** (it replaces a document window deliberately,
`git.lua:852-854`).
### Q#DC-4 — what happens when there is no document window? **(DECIDED in rev 3)**
**Revision 2 left this contradicting Q#DC-2 and it is the primary panel
@ -274,7 +332,8 @@ lane exists to remove.
whole point is to freeze the truth early and decide later.
- **The profile is declared at `commit_to`**, which is where Q#DC-2's
parameterization already lives. One place makes the decision, and it
is the place that knows.
is the place that knows. **Its exact call shape is Q#DC-5**, which
revisions 2 and 3 left unspecified.
- **A document-profile commit on a destination with no document pair is
REFUSED**, with a reason naming that, joining the four preflight
refusals rather than being a separate failure mode.
@ -307,6 +366,14 @@ incidental: no arguments is what keeps capture profile-blind.
asserted to **NOT refuse** under the panel profile. A deliberately
omitted check that has no test is indistinguishable from a check
someone forgot, and the next reader will restore it.
- **A legacy two-argument `commit_to(dest, body)` gets the DOCUMENT
profile** (Q#DC-5), witnessed by a check the panel profile omits —
a stale-buffer refusal. Asserting merely that it does not error would
pass on a call silently downgraded to the panel profile, which is the
regression that would quietly void Journey Stage 1a's guarantees.
- **An unrecognized profile string is REFUSED**, with a message naming
the accepted values — not silently treated as `"document"`.
- **A non-string profile is refused** the same way.
- **Capture SUCCEEDS with no document window** (Q#DC-4), returning a
destination whose document pair is absent — asserted as a successful
capture, not as `nil`.