Six findings from review, one of them a real defect.
**`canonicalize` could emit a path that exists nowhere.**
`p.display().to_string()` substitutes U+FFFD for non-UTF-8 bytes, so a
resolution landing on such a path returned a plausible-looking string
that does not exist on disk — worse than nil, because this value becomes
a server-affinity key through `file_uri_for` and would silently fail to
round-trip, while the doc promised nil for anything unresolvable. Now
`.and_then(|p| p.to_str().map(str::to_owned))`: unrepresentable is a
decline, matching how the fs layer already treats non-UTF-8 symlink
targets.
Pinned by a new acceptance case that reaches a non-UTF-8 target through
an **ASCII** symlink, so the input is representable and only the
resolved output is not — the case a UTF-8 check on the argument would
miss. Bitten: restoring `display()` fails it.
The other five:
- `on_response`'s doc comment now warns that registering against a
server with no attached buffer is fire-on-death, not fire-on-reply,
because the drain visits only attached sids. It looks exactly like a
hung request while debugging, and 3b is the first caller likely to
hit it.
- `deliver_response`'s comment still carried the pre-correction
rationale ("removed BEFORE invocation ... must not be re-entered") —
the claim the bite disproved. It now says what is true: removal is
unconditional, before-vs-after is unobservable without a re-entrant
drain, and the reachable bug is gating removal on a clean return.
- Dropped `server_attempt`'s unused second return.
- Deleted a vacuous assertion in the no-attachment test (counting `_G`
entries to assert "lua globals are readable") — scaffolding that
pinned nothing, the exact shape the project's own lesson flags.
- `#[cfg(unix)]` on the three symlink-dependent tests.
Gates re-run in full. The sweep's first pass tripped
`composition_overhead_under_ten_percent` at 18.8% against a 10% budget;
it passes 3/3 in isolation here, passes in isolation on main, and the
same run reported the realistic-frame overhead as **-4.6%** — a negative
figure is measurement noise, not added work. Nothing in this diff is on
the render path. Rerun of the full sweep: 3,189 across 93 suites, zero
failures.
Levi Neuwirth
a9ef257930