fix(session-notification): avoid Bun shell GC crash on Windows #543

JohnC0de · 2026-01-06T11:34:20Z

Summary

Fixes a segmentation fault crash on Windows caused by Bun's ShellInterpreter garbage collection bug when using ctx.$ (Bun shell template literals) for notifications.

Problem

Users on Windows + Bun v1.3.x experience crashes after running oh-my-opencode for extended periods:

Segmentation fault at address 0x337081E00E0
- interpreter.zig:1239: deinitFromFinalizer
- ZigGeneratedClasses.zig:19925: ShellInterpreterClass__finalize
- MarkedSpace.cpp:256: JSC::MarkedSpace::sweepPreciseAllocations

Root Cause

This is a confirmed Bun runtime bug (oven-sh/bun#23177, oven-sh/bun#24368):

The ShellInterpreter's finalizer doesn't properly clear WriteBarrier fields before destruction
JavaScriptCore's garbage collector accesses freed memory during heap sweep
Happens when shell operations are used repeatedly (e.g., notification sounds/toasts)

Trigger in oh-my-opencode

The session-notification hook uses ctx.$ to run PowerShell commands on Windows:

// Before (triggers Bun GC bug)
await ctx.$`${powershellPath} -Command ${toastScript}`.catch(() => {})

Every notification creates a new ShellInterpreter object. Over time, GC tries to clean these up → crash.

Solution

Replace all ctx.$ (Bun shell) calls with node:child_process.spawn:

// After (uses stable Node.js API)
await execCommand(powershellPath, ["-Command", toastScript]).catch(() => {})

This bypasses Bun's shell interpreter entirely, using Node.js's stable child_process module.

Changes

File	Change
`src/hooks/session-notification.ts`	Replace `ctx.$` with `execCommand()` using `spawn` from `node:child_process`
`src/hooks/session-notification.test.ts`	Update mocks to spy on `spawn` instead of `ctx.$`

Testing

✅ Typecheck passes
✅ All 11 session-notification tests pass
✅ Full test suite: 615 pass, 6 fail (pre-existing unrelated failures)

Upstream Status

Issue	Status	Notes
oven-sh/bun#23177	Closed (incomplete)	PR #23624 merged but didn't fully fix
oven-sh/bun#24368	Open	Same crash still happening in v1.3.1+
oven-sh/bun#24093	Open PR	Real fix using `jsc.JSRef` pattern

Workaround Alternative

Users can also disable the hook entirely:

{ "disabled_hooks": ["session-notification"] }

Summary by cubic

Replaced Bun shell template literals (ctx.$) with node:child_process.spawn in session-notification to prevent a Windows crash from Bun’s ShellInterpreter GC bug. Notifications and sounds now run reliably on Windows and consistently across platforms.

Bug Fixes
- Prevents segmentation fault on Windows with repeated notifications (Bun v1.3.x).
- Added execCommand wrapper and used it for osascript, notify-send, PowerShell, afplay/paplay/aplay.
- Updated tests to mock child_process.spawn and track notification commands.

^{Written for commit 970a679. Summary will update on new commits.}

…GC crash Replace Bun shell template literals (ctx.$) with node:child_process.spawn to work around Bun's ShellInterpreter garbage collection bug on Windows. This bug causes segmentation faults in deinitFromFinalizer during heap sweeping when shell operations are used repeatedly over time. Bug references: - oven-sh/bun#23177 (closed incomplete) - oven-sh/bun#24368 (still open) - Pending fix: oven-sh/bun#24093 The fix applies to all platforms for consistency and safety.

github-actions · 2026-01-06T11:34:33Z

All contributors have signed the CLA. Thank you! ✅
_{Posted by the CLA Assistant Lite bot.}

greptile-apps · 2026-01-06T11:36:37Z

Greptile Summary

Replaced Bun's shell template literals (ctx.$) with Node.js child_process.spawn in the session-notification hook to avoid a confirmed Bun runtime GC crash on Windows.

Changes:

Added execCommand() helper using node:child_process.spawn with proper error handling
Replaced all 7 ctx.$ calls (notifications + sound playback) with execCommand()
Updated test mocks to spy on spawn instead of the shell API
Maintains identical functionality while avoiding ShellInterpreter GC bug

Verification:

All 11 session-notification tests pass
No other files in the codebase use ctx.$
Workaround is valid until upstream Bun fix (oven-sh/bun#24093) is merged

Confidence Score: 5/5

This PR is safe to merge with no risk - it's a well-justified workaround for a confirmed upstream bug
The change addresses a confirmed Bun runtime bug with proper documentation and test coverage. The implementation correctly replaces shell operations with stable Node.js APIs while preserving functionality. All tests pass, the approach is sound, and the code quality is high.
No files require special attention

Important Files Changed

Filename	Overview
src/hooks/session-notification.ts	Replaced Bun shell (`ctx.$`) with `node:child_process.spawn` to avoid GC crash on Windows
src/hooks/session-notification.test.ts	Updated test mocks to spy on `spawn` instead of `ctx.$` template literal

Sequence Diagram

sequenceDiagram
    participant Session as OpenCode Session
    participant Hook as session-notification Hook
    participant Exec as execCommand()
    participant Spawn as node:child_process
    participant OS as OS (PowerShell/osascript/notify-send)

    Note over Session,OS: Before: Using Bun Shell (ctx.$)
    Session->>Hook: session.idle event
    Hook->>Hook: Wait idleConfirmationDelay
    Hook->>Hook: Check incomplete todos
    Hook->>OS: ctx.$`powershell -Command ...`
    Note over OS: ❌ Bun ShellInterpreter created
    OS-->>Hook: Notification sent
    Note over OS: ⚠️ GC attempts cleanup
    Note over OS: 💥 Segfault in finalizer

    Note over Session,OS: After: Using Node.js spawn
    Session->>Hook: session.idle event
    Hook->>Hook: Wait idleConfirmationDelay
    Hook->>Hook: Check incomplete todos
    Hook->>Exec: execCommand(powershell, ["-Command", script])
    Exec->>Spawn: spawn(cmd, args, {stdio: "ignore"})
    Spawn->>OS: Execute command
    OS-->>Spawn: Command completes
    Spawn-->>Exec: "close" event
    Exec-->>Hook: Promise resolves
    Note over Spawn: ✅ No ShellInterpreter
    Note over Spawn: ✅ Safe GC

greptile-apps · 2026-01-06T11:36:38Z

Greptile's behavior is changing!

From now on, if a review finishes with no comments, we will not post an additional "statistics" comment to confirm that our review found nothing to comment on. However, you can confirm that we reviewed your changes in the status check section.

_{This feature can be toggled off in your Code Review Settings by deselecting "Create a status check for each PR".}

cubic-dev-ai

No issues found across 2 files

Confidence score: 5/5

Automated review surfaced no issues in the provided summaries.
No files require special attention.

JohnC0de · 2026-01-06T14:45:26Z

I have read the CLA Document and I hereby sign the CLA

…ging Adds a lightweight, off-by-default tracing system to help diagnose Windows crashes. Features: - Ring buffer-based tracer with JSONL output - Traces all spawn operations (session-notification, LSP, subagents) - Crash handlers (uncaughtException, unhandledRejection, signals) - debug-bundle CLI command for diagnostic collection - Automatic sensitive data redaction - Enable via OMO_DEBUG=1 environment variable This helps identify the root cause of crashes that persist after PR code-yeongyu#543. Refs: oven-sh/bun#25798, anomalyco/opencode#3267

…iagnosed) This reverts commit 4a38e70 (PR code-yeongyu#543) and 2064568 (follow-up fix). ## Why This Revert The original diagnosis was incorrect. PR code-yeongyu#543 assumed Bun's ShellInterpreter GC bug was causing Windows crashes, but further investigation revealed the actual root cause: **The crash occurs when oh-my-opencode's session-notification runs alongside external notification plugins (e.g., @mohak34/opencode-notifier).** Evidence: - User removed opencode-notifier plugin → crashes stopped - Release version (with original ctx.$ code) works fine when used alone - No widespread crash reports from users without external notifiers - Both plugins listen to session.idle and send concurrent notifications The real issue is a conflict between two notification systems: 1. oh-my-opencode: ctx.$ → PowerShell → Windows.UI.Notifications 2. opencode-notifier: node-notifier → SnoreToast.exe A proper fix will detect and handle this conflict gracefully. Refs: code-yeongyu#543, oven-sh/bun#23177, oven-sh/bun#24368 See: docs/CRASH_INVESTIGATION_TIMELINE.md (in follow-up commit)

…tification plugins When oh-my-opencode's session-notification runs alongside external notification plugins like opencode-notifier, both listen to session.idle and send concurrent notifications. This can cause crashes on Windows due to resource contention between different notification mechanisms: - oh-my-opencode: ctx.$ → PowerShell → Windows.UI.Notifications - opencode-notifier: node-notifier → SnoreToast.exe This commit adds: 1. External plugin detection (checks opencode.json for known notifiers) 2. Auto-disable of session-notification when conflict detected 3. Console warning explaining the situation 4. Config option 'notification.force_enable' to override Known notification plugins detected: - opencode-notifier - @mohak34/opencode-notifier - mohak34/opencode-notifier This is the actual fix for the Windows crash issue previously misdiagnosed as a Bun.spawn GC bug (PR code-yeongyu#543). Refs: code-yeongyu#543

Documents the investigation journey from initial misdiagnosis (Bun GC bug) to discovering the actual root cause (notification plugin conflict). Key findings: - PR code-yeongyu#543 was based on incorrect assumption - The real issue is concurrent notification plugins - oh-my-opencode + opencode-notifier = crash on Windows - Either plugin alone works fine

… plugin conflict detection (#575) * revert: undo PR #543 changes (bun shell GC crash was misdiagnosed) This reverts commit 4a38e70 (PR #543) and 2064568 (follow-up fix). ## Why This Revert The original diagnosis was incorrect. PR #543 assumed Bun's ShellInterpreter GC bug was causing Windows crashes, but further investigation revealed the actual root cause: **The crash occurs when oh-my-opencode's session-notification runs alongside external notification plugins (e.g., @mohak34/opencode-notifier).** Evidence: - User removed opencode-notifier plugin → crashes stopped - Release version (with original ctx.$ code) works fine when used alone - No widespread crash reports from users without external notifiers - Both plugins listen to session.idle and send concurrent notifications The real issue is a conflict between two notification systems: 1. oh-my-opencode: ctx.$ → PowerShell → Windows.UI.Notifications 2. opencode-notifier: node-notifier → SnoreToast.exe A proper fix will detect and handle this conflict gracefully. Refs: #543, oven-sh/bun#23177, oven-sh/bun#24368 See: docs/CRASH_INVESTIGATION_TIMELINE.md (in follow-up commit) * fix(session-notification): detect and avoid conflict with external notification plugins When oh-my-opencode's session-notification runs alongside external notification plugins like opencode-notifier, both listen to session.idle and send concurrent notifications. This can cause crashes on Windows due to resource contention between different notification mechanisms: - oh-my-opencode: ctx.$ → PowerShell → Windows.UI.Notifications - opencode-notifier: node-notifier → SnoreToast.exe This commit adds: 1. External plugin detection (checks opencode.json for known notifiers) 2. Auto-disable of session-notification when conflict detected 3. Console warning explaining the situation 4. Config option 'notification.force_enable' to override Known notification plugins detected: - opencode-notifier - @mohak34/opencode-notifier - mohak34/opencode-notifier This is the actual fix for the Windows crash issue previously misdiagnosed as a Bun.spawn GC bug (PR #543). Refs: #543 * docs: add crash investigation timeline explaining the real root cause Documents the investigation journey from initial misdiagnosis (Bun GC bug) to discovering the actual root cause (notification plugin conflict). Key findings: - PR #543 was based on incorrect assumption - The real issue is concurrent notification plugins - oh-my-opencode + opencode-notifier = crash on Windows - Either plugin alone works fine * fix: address review feedback - add PowerShell escaping and use existing JSONC parser - Add back single-quote escaping for PowerShell soundPath to prevent command failures - Replace custom stripJsonComments with existing parseJsoncSafe from jsonc-parser - All 655 tests pass --------- Co-authored-by: sisyphus-dev-ai <[email protected]>

This was referenced Jan 6, 2026

Segmentation fault at address 0x334941E0140 oh no: Bun has crashed. This indicates a bug in Bun, not your code. oven-sh/bun#24368

Open

Segfault in ShellInterpreter finalizer during garbage collection oven-sh/bun#23177

Closed

cubic-dev-ai bot reviewed Jan 6, 2026

View reviewed changes

github-actions bot added a commit that referenced this pull request Jan 6, 2026

@JohnC0de has signed the CLA in #543

6f1cabd

code-yeongyu merged commit 4a38e70 into code-yeongyu:dev Jan 6, 2026
4 of 5 checks passed

This was referenced Jan 7, 2026

feat(debug): add comprehensive crash tracing system for Windows debugging #571

Closed

fix(lsp): add resilient handling for missing LSP server binaries #572

Open

JohnC0de mentioned this pull request Jan 7, 2026

fix(session-notification): revert PR #543 and add proper notification plugin conflict detection #575

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Summary

Problem

Root Cause

Trigger in oh-my-opencode

Solution

Changes

Testing

Upstream Status

Workaround Alternative

Related

Summary by cubic

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Greptile Summary

Confidence Score: 5/5

Important Files Changed

Sequence Diagram

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