bug: hooks use invalid decision value "allow" — should be "approve"

[sha2fiddy]

PR #786 changed the save and precompact hooks from "decision": "block" to "decision": "allow" to stop the agent from writing in chat. The intent was right but "allow" isn't a valid value for the top-level decision field.

The fix is "allow" → "approve".

Update: "approve" isn't valid here either — it's a deprecated PreToolUse-only alias (maps to "allow" in hookSpecificOutput.permissionDecision). The top-level decision field only recognizes "block". To not block, you return empty JSON ({}).

Affected files:

• hooks/mempal_save_hook.sh (line 159)
• hooks/mempal_precompact_hook.sh (line 74)

Fix: Replace the full JSON output block with {} when not blocking. Only use {"decision": "block", "reason": "..."} when the hook actually needs to prevent the action.

Note: PR #863 already caught this — mvalentsev replaced the invalid {"decision": "allow", ...} with {} in hooks_cli.py. The standalone bash hooks still need the same treatment.

Related: #856, #858 (report compaction symptoms that may stem from this)

[mvalentsev]

Good catch, thanks. Our #863 was indeed using the wrong value.

One correction though: "approve" isn't valid here either. It's a deprecated alias for "allow" in PreToolUse permissionDecision, not a top-level decision value. The top-level decision field only recognizes "block" -- to not block, you return empty JSON ({}).

Just pushed a fix to #863: {"decision": "allow", ...} replaced with {}.

The standalone bash hooks in hooks/ have the same problem ("decision": "allow" on lines 74 and 159). Those need a separate fix since they're outside our PR scope.

[sha2fiddy]

You're right, thanks for the correction. I double-checked the hooks spec — top-level decision only supports "block", and non-blocking hooks should just return {}. Updated the issue description.