fix(pi): expire and cancel extension approvals

[StiensWout]

Problem

Timed Pi extension dialogs stayed pending in T3 after Pi stopped waiting, and startup dialogs could survive transport death.

Change

Expire the request, node and work item together; reject late answers before sending or caching approval; cancel timer fibers on resolution and teardown. Pass the native operation signal into bridge confirmations.

Scope and approval

Maintainer-requested Pi support follow-up. Scope is expiration and cancellation of existing Pi extension dialogs.

Verification

Validation: 91 adapter/bridge tests, Pi typecheck and scoped lint/format checks passed. Timeout coverage uses the test clock and observed request milestones.

_{Prepared for Wout by gpt-6.1-sol in Codex.}

[macroscopeapp]

Approvability

Verdict: Not approved

Macroscope's review found this PR not approvable — This is a focused Pi provider bug fix with targeted coverage for timeout, teardown, stale-response, and abort-signal behavior. It changes the lifecycle of extension and tool approvals, which is a security-sensitive execution control and warrants human review.

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[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

• Configuration used: Path: .coderabbit.config.ts
• Review profile: CHILL
• Plan: Advanced
• Run ID: 1224eecc-be63-4fe7-8064-29f1e283f0ff

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📥 Commits

Reviewing files that changed from the base of the PR and between 8c777fb and f9e1bd7.

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📒 Files selected for processing (4)

• packages/provider-pi/src/server/adapter.test.ts
• packages/provider-pi/src/server/adapter.ts
• packages/provider-pi/src/server/mcpExtensionSource.test.ts
• packages/provider-pi/src/server/mcpExtensionSource.ts

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📝 Walkthrough

Walkthrough

The Pi adapter now expires timed extension UI requests, rejects late responses, and cancels pending prompts on specified transport failures. Tool-call confirmation now receives the call's abort signal.

Changes

Prompt lifecycle

Layer / File(s)	Summary
Prompt expiration setup packages/provider-pi/src/server/adapter.ts	Pending prompts track an optional deadline and expiration fiber. Requests with a nonzero timeout schedule expiration; cancellation interrupts the fiber.
Expiration and transport-failure handling packages/provider-pi/src/server/adapter.ts, packages/provider-pi/src/server/adapter.test.ts	The adapter cancels expired prompts and rejects answers at or after the deadline. When the event pump fails with no active turn, it cancels pending prompts. Tests cover timeout behavior, stale answers, and startup cancellation.

Tool-call confirmation signal

Layer / File(s)	Summary
Pass the abort signal to confirmation packages/provider-pi/src/server/mcpExtensionSource.ts, packages/provider-pi/src/server/mcpExtensionSource.test.ts	The confirmation prompt receives the tool call's abort signal. The test verifies that the same signal is passed.

Priority: ➖ Normal

Estimated code review effort: 3 (Moderate) | ~20 minutes

Change: Bug fix

Suggested reviewers: juliusmarminge

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Merge Risk | ⚪ Minimal · up to f9e1b

Merge Risk: ⚪ Minimal · up to f9e1b

The timer-assignment concern does not block merging: responses cannot enter that window. No actionable merge-blocking issue remains identified.

Security Architecture Review

Security architecture risk: 🔵 Low · up to f9e1b

The change tightens approval expiration and cleanup without expanding permissions. One execution-boundary question remains: whether cancelled or failed confirmations reliably prevent tool execution.

Retained concerns

• Low · security · inferred: The new cancellation path delegates enforcement of rejected confirmations to the native Pi executor. Available evidence establishes explicit denial when confirmation returns false, but not whether an aborted or rejected confirmation prevents downstream tool execution. This is a contract uncertainty, not a verified bypass.

Security review details

Security Blast Radius

• inferred — The relevant exposure is execution of tools already governed by the Pi session's permission mode. Cancellation propagation does not add tool identities, credentials or authorization exemptions in the changed approval hook.

Security Findings and Attack Paths

• inferred — A possible approval-bypass path would require native cancellation to reject confirmation and the native dispatcher to continue tool execution despite that rejection. Neither behavior is established by available source, so this remains an unresolved enforcement contract rather than a demonstrated attack path.

Trust Boundaries and Controls

• observed — Tool names and inputs still reach the existing blocking confirmation hook. Full-access, known read-only tools, builtin tool search and auto-accepted edits retain their base behavior. Other tools require confirmation, and a false result explicitly blocks execution.

Resilience and Maintainability Implications

• observed — Transport failure now reaches prompt cancellation both for startup dialogs and through active-turn finalization. This reduces stranded approval state without changing the existing active-turn finalization route.

Hardening Proposals

• proposed — Validate the native cancellation contract with aborted and rejected confirmations, demonstrating that the downstream tool is not executed. The existing mock establishes signal propagation and explicit false-result blocking, not native rejection enforcement.

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Pre-merge checks | 4

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description check		The description covers the problem, the implementation, scope, and focused verification. It does not provide a link or approval comment for the maintainer request, but it identifies the request and cl…
Title check		The title clearly and concisely describes the main change: expiring and cancelling Pi extension approvals.
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create a new PR

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