fix: settle shell completion on process exit instead of pipe EOF

[linsmod]

Issue for this PR

Closes#20902

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

The bash/shell tool reports a command as done only when the spawned child's stdio pipes fully close (close event). When a command leaves a background descendant alive (gradle daemon, adb server, dev server, Start-Process children), that descendant inherits the pipe and keeps it open after the direct child exits, so the tool never sees EOF and blocks until timeout/abort. Same root cause as #22012, #24784, #29822, #32504, #37838, #42524, #43910.

It's two problems stacked:

1. cross-spawn-spawner.ts settles exitCode from close instead of exit.
2. Callers still gate completion on stream EOF — AppProcess.run (Effect.all([collectStream, exitCode])) and the V1 ShellTool stream reader both wait for the pipe to close.

Changes:

• Settle exitCode from the exit event, keep close as a fallback.
• process.ts: new collectBounded — reads the stream concurrently (avoids a pipe-full deadlock), waits for process exit, then a short 2s drain window before returning captured output. A shared accumulator preserves partial output if the window expires.
• opencode/src/tool/shell.ts: after the direct child exits, drain briefly then interrupt the stream-reader fiber so the effect scope closes.
• tui/src/util/transcript.ts: /copy now renders captured output for aborted/error tool parts.

Completion is now anchored to the direct process exiting instead of pipe EOF, so a surviving grandchild can't block the tool; the bounded drain still captures all in-flight output.

Related fix attempt #42275 only covers the first layer and explicitly leaves callers waiting for stream completion; this PR closes that gap. The background-shell features #40005 / #33310 are intentionally out of scope (managed background jobs remain explicitly opt-in).

How did you verify your code works?

• bun typecheck: @opencode-ai/core, opencode, @opencode-ai/tui all pass.
• bun test: process (32), tool-bash, cross-spawn-spawner (incl. new regression: exitCode resolves on direct-child exit while a descendant holds the pipe open), shell tool (66, incl. new regression: foreground exits but a descendant holds the pipe 6s → tool returns in < 8s), transcript (20, incl. aborted-tool output), processor-effect (17).
• --single build passes the smoke test.
• Reproduced the real hang (gradle + adb install on Windows): output completed with "Success", the tool part stayed running ~6 min until abort, then ended as error: "Tool execution aborted" with no output in /copy. The same command returns promptly in an interactive pwsh because stdout is a console handle, not a pipe.

Screenshots / recordings

N/A — no UI change.

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

[github-actions]

Hey! Your PR title fix(core,opencode,tui): settle shell completion on process exit instead of pipe EOF doesn't follow conventional commit format.

Please update it to start with one of:

• feat: or feat(scope): new feature
• fix: or fix(scope): bug fix
• docs: or docs(scope): documentation changes
• chore: or chore(scope): maintenance tasks
• refactor: or refactor(scope): code refactoring
• test: or test(scope): adding or updating tests

Where scope is the package name (e.g., app, desktop, opencode).

See CONTRIBUTING.md for details.

[github-actions]

The following comment was made by an LLM, it may be inaccurate:

Found a related PR:

PR #42275 — fix(core): resolve child process exit signal on exit event

This PR is directly related but incomplete compared to PR #44601. According to the PR description itself, #42275 only fixes the first layer (spawner exitCode settles on exit) but leaves callers still waiting for stream completion, so continuously-outputting descendants still hang. PR #44601 builds on this by adding the collectBounded layer to bound stream collection and prevent the hang at the caller level.

No other duplicate PRs found for this specific issue.

[github-actions]

Thanks for updating your PR! It now meets our contributing guidelines. 👍