fix(hooks): don't emit invalid permissionDecision 'defer' — it swallows the AskUserQuestion widget

[jawadakram20]

The bug

question-preference-hook returns {"permissionDecision":"defer"} on its no-opinion path, intending "let the permission flow continue."

defer is not in Claude Code's PreToolUse schema, which accepts only allow / deny / ask. As of Claude Code 2.1.14 the unrecognized value is interpreted as defer the tool call: the call is dropped and logged as a hook_deferred_tool attachment. It never executes.

For AskUserQuestion this means the question widget never renders. The user sees nothing at all, and the agent is left waiting on an answer that can never arrive.

Captured in a real transcript:

tool_use          AskUserQuestion  toolu_01PWVYTunnejtJTZv3SF6Bsw
hook_success      PreToolUse:AskUserQuestion
                  stdout: {"hookSpecificOutput":{"hookEventName":"PreToolUse","permissionDecision":"defer"}}
hook_deferred_tool  AskUserQuestion   <-- call swallowed here
user              "questions are not loading"

Blast radius

This is not limited to users with plan-tune preferences configured. defer() is the default path for every non-auto-decidable question:

• no preference set
• recommendation marker missing
• always-ask preference
• one-way-door safety override
• empty/unparseable stdin (crash safety)
• non-AUQ tool names (defensive)

So AskUserQuestion is broken for essentially every user on Claude Code 2.1.14 with gstack installed.

The fix

Omit permissionDecision entirely in defer(). That is the correct "no opinion" signal — normal permission flow continues, and additionalContext (the memory-cache injection) is still delivered.

The deny() paths are untouched: never-ask auto-decide and the Conductor prose redirect still enforce exactly as before.

Docs

docs/spikes/claude-code-hook-mutation.md documented "defer" — let permission flow continue as a valid value. That stale assumption is how this got written, so it's corrected here to prevent reintroduction.

Tests

Defer-path assertions changed from toBe('defer') to toBeUndefined(), matching the corrected contract.

bun test test/question-preference-hook.test.ts \
         test/memory-cache-injection.test.ts \
         test/gstack-question-log.test.ts

 51 pass
 0 fail
 101 expect() calls

Verified end-to-end on Claude Code 2.1.14: with the patch applied, AskUserQuestion renders and returns answers normally. Both PostToolUse AUQ hooks (question-log-hook, auq-error-fallback-hook) were also checked and are unaffected.

[trunk-io]

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[jawadakram20]

/trunk merge

[trunk-io]

An error occurred while submitting your PR to the queue: Only users that are a part of this repo's Trunk organization or have write permissions to the repo can submit a PR to the queue

[jawadakram20]

Heads up for maintainers: I'm an outside contributor pushing from a fork, so I can't submit this to the Trunk queue myself — my /trunk merge above was rejected with Only users that are a part of this repo's Trunk organization or have write permissions to the repo can submit a PR to the queue. (The bot prompt is posted automatically on fork PRs too, hence the confusion.)

CI also hasn't run yet — workflows from first-time fork contributors need the "Approve and run" click, so the combined status is still pending with 0 reported checks.

Whenever someone with write access has a moment, this needs an approve-and-run and then an enqueue from your side. Happy to rebase or adjust anything in the meantime.

For convenience, the test run locally on this branch:

bun test test/question-preference-hook.test.ts \
         test/memory-cache-injection.test.ts \
         test/gstack-question-log.test.ts

 51 pass
 0 fail
 101 expect() calls