fix(core): backport transport and process-exit cleanup - #410

Closes https://github.com/swxtchio/swx-opencode/issues/393.

Backport the assigned transport and process-lifecycle behavior in the fork's existing owners. Preserve request options, caller cancellation, configured deadlines, fork #303's generation-progress watchdog, fork #380 cancellation cleanup, and intentional descendant release.

Donor coverage

• anomalyco/opencode#55149 (52a10f573f1da5103c85990da9341e3645a39365), local cherry-pick ca3abb1290: the assigned TUI/run/mini fetch override is complete through packages/core/src/no-timeout-fetch.ts, packages/tui/src/context/sdk.tsx, and packages/opencode/src/cli/cmd/run.ts. The donor's existing-session shell-failure UI recovery is unassigned and excluded; payload status is partial.
• anomalyco/opencode#55007 (460c626acd9e3de8fdffc27bde99bb5f070bb70f), local cherry-pick 379832391b: the native override is wired at packages/core/src/effect/app-node-platform.ts's actual RequestExecutor composition; payload status is complete.
• anomalyco/opencode#59411 (e2bc79dc0bae112b79ab780f7c1a63db8a7f7dae), local cherry-pick 31ccedc31b: detached POSIX groups are synchronously terminated while cleanup remains owed. packages/tui/src/app.tsx routes terminal SIGHUP through renderer shutdown; packages/tui/src/terminal-signal.ts preserves nohup's ignore without a TTY. The upstream CLI shutdown-deadline module is absent and not imported; payload status is partial, assigned behavior complete.

Bun 1.4.4 and install

The official bun-linux-aarch64.zip SHA-256 baa6bb36f51d6e58561e02bbea825038a9df454f673d6d776e8bbf86f8c7850e matched the committed Nix SRI sha256-uqa7NvUdblhWHgK76oJQOKnfRU9nPW13bou/hvjHhQ4=. The extracted binary reported Bun 1.4.4, revision 1.4.4+38afee6c8. bun install --frozen-lockfile passed with the verified binary and reported no lockfile changes (2,444 installs checked across 2,843 packages).

Core, OpenCode, and TUI package-local bun typecheck each passed in bounded, memory-capped background scopes. OpenCode typecheck was repeated after the test-only server-readiness bound adjustment and passed.

Round-one review coverage

1. CrossSpawnSpawner sends acknowledged process-group acquisition/release events to the TUI server Worker. Worker shutdown kills and confirms its remaining groups before replying; TuiThreadCommand keeps the recorded PGID ledger for bounded timeout, Worker-error and owner-exit backstops. The focused integration test drives the real packages/opencode/src/cli/tui/worker.ts RPC path for both shutdown acknowledgement and a blocked-shutdown parent backstop.
2. TUI SDK/SSE and Mini attach tests hold real requests while a default fetch control expires under a child Bun 1.4.4 process configured with BUN_CONFIG_HTTP_IDLE_TIMEOUT=2; they then release the real event or session response. The attached-run acceptance uses the same short child-process timeout and confirms persisted session output.
3. SIGHUP fixtures now report only observed behavior: the real terminal TUI fixture verifies lifecycle cleanup, the nohup fixture proves ignored-SIGHUP survival, and a non-TTY non-nohup fixture proves the OS default action without asserting graceful cleanup.
4. The default unit suite no longer waits multiple minutes: held-request witnesses use bounded child Bun processes and short release windows. Before that change, unmodified-default runs had already observed native and attached-run completion after 374.96s and 418.23s respectively.
5. CHANGESET.md now records the replace-not-merge native request policy, high-level option preservation, acknowledged Worker group ownership, SIGHUP distinctions, and test coverage.

Focused validation (verified Bun 1.4.4)

• Core native idle witness: 1 pass, 12.18s; CrossSpawnSpawner ownership/scope-release slice: 5 pass, 17.92s.
• Mini attach witness: 1 pass, 21.13s; attached-run witness: 1 pass, 22.19s.
• TUI SDK/SSE witness: 1 pass, 15.31s; terminal/nohup/default SIGHUP fixtures: 3 pass, 7.90s.
• Real TUI Server Worker process-group shutdown/backstop test: 1 pass, 22 assertions.
• Core, OpenCode, and TUI package typechecks passed in bounded scopes; the normal pre-push Turbo typecheck also passed 30/30 with concurrency limited to one.

Focused preservation and removal proofs

• Under Bun 1.4.4, the core fetch-helper tests, Mini attach construction, TUI SDK event client, TUI terminal/nohup SIGHUP cases, Core native caller-expiry case, abrupt-owner-exit group cases, and the fix(core): reap shell process groups on cancellation #380 scope-release descendant-reaping case passed.
• The fix(opencode): bound stalled provider streams and interrupts #303 Foundry stall case passed with the generation-progress timeout restored; the slow-reasoning and Chat Completions/tool-argument progress cases passed. An earlier slow-reasoning run hit the fixture's 2-second progress deadline; the final isolated uninstrumented run passed.
• Replacing noTimeoutFetch with fetch(request, init) made the Mini and TUI SDK regressions fail at timeoutDisabled (false, expected true). The attached-run regression also failed under a red-only BUN_CONFIG_HTTP_IDLE_TIMEOUT=2 run with the helper removed; its green acceptance used the unmodified default.
• Removing Layer.provide(withoutBunTimeout) made the native composition regression observe timeout: 1 instead of false. Removing the spawner's exit hook made live and cleanup-owed group cases fail with recorded members still alive. Removing the TUI non-terminal guard made the nohup case fail; removing terminal handler registration made the PTY case fail. Disabling the fix(opencode): bound stalled provider streams and interrupts #303 progress timer made the stalled-Foundry case fail inside its bound. Each behavior was restored and its focused positive case passed.

Round-one changed tests: packages/core/test/effect/app-node-platform.test.ts, packages/core/test/effect/cross-spawn-spawner.test.ts, packages/opencode/test/cli/run/mini-attach.test.ts, packages/opencode/test/cli/run/run-process.test.ts, packages/opencode/test/cli/tui/worker-process-group.test.ts, packages/tui/test/cli/tui/sdk-transport.test.tsx, and packages/tui/test/app-lifecycle.test.tsx. Supporting process fixtures are packages/opencode/test/cli/run/mini-attach-worker.ts, packages/opencode/test/cli/tui/worker-process-group-worker.ts, packages/tui/test/fixture/sighup-ignore-worker.ts, and packages/tui/test/fixture/sighup-terminal-worker.ts.

Handoff

Current pushed head: b05423513beb168f45c29cb11e3aaf5cdc7c631f, on fm/oc-transport-exit-393, based on the no-rebase merge of origin/swxtch through 02013d1c77 (#407). PR #410 remains draft. The commit-identity gate passed on the merged base range. This repository has no bin/fm-lint.sh. Do not merge the PR or mark it ready; Firstmate owns review and final-suite admission.