fix(opencode): settle interrupted prompt admissions

[rynfar]

Interrupted OpenCode turn admission can leave Stop waiting forever, holding up thread deletion and later thread creation. Complete the send-owned submission receipt on every exit, including interruption before the prompt worker starts.

Adapted source: e518866d28603da273a9357516dd1aef919f1353 (T3 #12003), in successor bound ab099178a7b7f9728843e90fc95ed90bb61d710d..0fcd5f90611451cca842689faea53b5450c022da. Related tracking: #865. Its existing 127-source range and review cursor remain unchanged.

Pylon captures this send's deferred rather than reading whichever admission is currently on the session. The finalizer runs inside the prompt permit; session incarnation, cancellation, recovery and remote-abort behavior remain in place. The existing prompt-worker finalizer still handles submitted prompts.

Validation: the gated regression times out before the fix and passes after it; it confirms no prompt was submitted and Stop removes the session and closes the runtime. All 135 OpenCode adapter tests pass, along with server typecheck (existing Effect suggestions only), scoped lint, format and diff checks. This is provider-local behavior shared by web, desktop and mobile in local, remote and tunnel modes; no wire schema, persistence migration, or other provider change. A real OpenCode process was not exercised. Independent PR review and final-head CI remain required before merge.

Model: GPT-6.1 Sol. Harness: Codex in Pylon.

---

^{Need help on this PR? Tag @codesmith-bot with what you need. Autofix is disabled.}

[github-actions]

Thread transfer impact

✅ Thread transfer remains within every enforced ceiling.

Provider	Metric	Main baseline	This PR	Impact	PR ceiling
Codex	Total thread wire	14.0 KiB	14.0 KiB	+28 B (+0.2%)	15.1 KiB	✅
Codex	Thread snapshot wire	7.3 KiB	7.3 KiB	+2 B (+0.0%)	7.3 KiB	✅
Codex	Live turn WebSocket wire	6.7 KiB	6.8 KiB	+26 B (+0.4%)	7.8 KiB	✅
Codex	Live turn WebSocket decoded	58.0 KiB	58.0 KiB	+44 B (+0.1%)	66.4 KiB	✅
Codex	Live turn messages	9	10	+1 (+11.1%)	21	✅
Claude	Total thread wire	14.0 KiB	14.0 KiB	+10 B (+0.1%)	15.1 KiB	✅
Claude	Thread snapshot wire	7.3 KiB	7.3 KiB	−13 B (−0.2%)	7.3 KiB	✅
Claude	Live turn WebSocket wire	6.7 KiB	6.8 KiB	+23 B (+0.3%)	7.8 KiB	✅
Claude	Live turn WebSocket decoded	58.9 KiB	58.9 KiB	+44 B (+0.1%)	66.4 KiB	✅
Claude	Live turn messages	9	10	+1 (+11.1%)	21	✅

Baseline: 95ab96b · PR result: 85b7d2a · Source CI: success

Scenario and decoded snapshot size

10 historical turns, 5 command tools per turn, 878.9 KiB retained MCP result per historical turn, and a 1.05 MiB retained result in the measured turn.

• Codex decoded thread snapshot: 115.7 KiB
• Claude decoded thread snapshot: 116.4 KiB

Updated in place by a trusted workflow. PR artifacts are strictly validated and never executed.