Revision 8 of `docs/destination-capture-framing.md`, replacing the
revision-7 design at `ca72461`, plus the invalid-UTF-8 profile hole.
The framing now carries §3's enumeration, performed.
THE BLOCKER, unchanged. The `"panel"` commit profile skips preflight
checks 2-4 on the claim that a panel result never touches a document
window. Panel placement FALLS BACK into an ordinary document window
when the frontend is not `panel_capable` or its one side slot is
dedicated elsewhere, and installs the result there --- so a `"panel"`
commit could replace a NEWER document with every stale-intent guard
skipped.
TWO REJECTED SHAPES, kept in the framing as the record of why not
those. Revision 6 predicted the fallback at preflight and argued the
body could not change it; false, because refusing `await` stops another
COROUTINE interleaving, not the body's own synchronous statements.
Revision 7 (`ca72461`) moved enforcement to the placement boundary;
that breaks the invariant `commit_to` exists for --- `docs/agent-handoff.md`
requires it to preflight BEFORE the callback, because a body creates
buffers, handles and paint long before it asks to display anything, so
"validating at display time is four mutations too late". A refusal
arriving after all of that is a partial commit with an error return.
REVISION 8 DOES NEITHER. The preflight stays exactly where it was, and
the mutations that would invalidate it are REFUSED AT THE ATTEMPT ---
the same shape as `Handle:await` being refused inside a commit scope,
for the identical reason: something that would invalidate the scope's
guarantee is rejected outright rather than predicted around or caught
late. With them refused, the fallback never comes into existence.
THE ENUMERATION, PERFORMED --- this is the load-bearing part, and it is
closed for a structural reason rather than because inspection ran out
of ideas. Full working in the framing §3.
`resolve_placement` reaches `Ordinary` from a side request through
exactly two branches, so only two pieces of state are levers at all:
`panel_capable`, and the one side window's `dedicated`.
`panel_capable` is UNREACHABLE from a body: written only where a
`FrontendView` is constructed, and nothing in `src/lua_bindings/`
constructs, registers or unregisters one --- `register_frontend_view`
has callers only in `daemon.rs` and core unit tests.
`dedicated` has eight writes. Five are reachable: `apply_placement`'s
`Side` created, replacing and non-replacing arms, and `set_params`. Two
`Ordinary` arms are harmless --- every `Ordinary` target is filtered
`!is_side`, and one only ever clears the flag. One is a unit test.
Closing the side window is NOT a route, checked rather than assumed:
with no side leaf `side_window_for` returns `None` and placement
CREATES a fresh panel instead of falling back. `panel_hidden` is not
consulted by placement, and `params.side` is unreachable.
`quit_window`'s `QuitAction::Restore { dedicated: true }` is
UNREACHABLE, and this was the surprise --- it looked like a route with
no `dedicated` argument at the call site at all. `Restore` is stored
only on a REPLACING side placement, and a dedicated slot can never be
the target of one: a side request with a different buffer falls through
to `Ordinary`, and an exact-target request is refused by
`window_accepts_buffer`. Guarded anyway, labelled defensive, because
its unreachability is emergent from two rules in another function.
GUARDS SITED WHERE THE PROPERTY CONVERGES. All three `Side` arms are
reached through `apply_placement`, which has EXACTLY ONE caller --- so
one guard in `display_buffer` covers every request-driven dedication,
including spellings that do not exist yet. `set_params` is a genuinely
separate write and is guarded separately; dedication does NOT converge
before the field itself, and that is stated rather than papered over.
`Window::params.dedicated` is a public field, so the compiler does not
enforce the funnel --- the acceptance rows are what would catch a new
direct writer.
WHAT IS DELIBERATELY NOT REFUSED. The document profile is untouched:
constraining its body would newly refuse dired's own documented panel
path, a preservation-suite stop signal. Dedicating a DOCUMENT window is
still allowed, since it cannot change which of panel-or-document a side
request resolves to. And falling back is still allowed --- a frontend
that cannot render a panel degrades gracefully exactly as today,
because this refuses the mutation that MANUFACTURES a fallback, never
the fallback itself.
THE SECOND HOLE. `commit_profile` did `name.to_str()?`, but Lua strings
are BYTE strings, so `string.char(255)` hit mlua's generic UTF-8 error
before `BAD_COMMIT_PROFILE` was constructed --- the same reachability
class as the `Option<String>` defect revision 5 fixed, one layer down.
Bytes now, with the row asserting on message content.
TESTS: 12 pins. The inside-the-body test is ONE ROW PER REACHABLE WRITE
SITE, not per call spelling, because one spelling reaches three
different writes: `set_params`, and `display{side, dedicated}` in each
of the created, replacing and non-replacing arms. Each asserts the
three things revision 8 requires --- the dedication call is refused, the
slot is still undedicated afterwards, and nothing partial was installed
(no `*result*` buffer, panel unchanged, document unchanged).
Mutation-checked per guard: deleting the `display_buffer` guard fails
all three display rows, verified INDIVIDUALLY by rotating each to the
front so the first failure cannot mask the rest; deleting the
`set_params` guard fails only that row.
THREE FRAMING CORRECTIONS ride along, all of them cases of the document
teaching something it later argues against. Section 3 stated the
disproved premise unconditionally --- "the panel case would inherit a
check about a window it never touches" --- a hundred lines before
correcting it, so a reader met the wrong claim first; it is now
qualified at the point of the claim, and section 2 carried the same
unconditional form one section earlier ("it lands in the bottom panel")
and now says it REQUESTS one. The handoff citation was written "section
748" twice when it is LINE 748, and this document's authority is that
its citations can be followed. And the "not asserted exhaustive" hedge
on the route list is retired: the enumeration is closed structurally,
because `resolve_placement` reaches `Ordinary` from a side request
through exactly two branches.
`journey_acceptance` (47) and `dired_acceptance` (31) pass UNCHANGED.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016bqGA6s9tTUFzYpbeW3tai
Levi Neuwirth
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