fix(hooks): include required hookEventName in hookSpecificOutput JSON

outputWithContext() emitted a hookSpecificOutput object without the
required hookEventName field, so Claude Code rejected the hook output
("hookSpecificOutput is missing required field hookEventName") and
dropped the context the SessionStart, UserPromptSubmit, and PostToolUse
hooks tried to inject. Thread the event name through the helper; each
caller now passes its own (SessionStart / UserPromptSubmit / PostToolUse).
Existing emission tests now assert hookEventName per event.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VmHCQjJHUyWwxGAVVjNLgp

CHANGELOG.md

@@ -2,6 +2,18 @@
 
 All notable changes to this project will be documented in this file.
 
+## [Unreleased]
+
+### Fixed
+
+- **Hooks emitted invalid JSON, so Claude Code dropped their injected
+  context.** `outputWithContext()` wrote a `hookSpecificOutput` object
+  without the required `hookEventName` field; the harness rejected it
+  ("hookSpecificOutput is missing required field hookEventName") and
+  discarded the context the SessionStart, UserPromptSubmit, and PostToolUse
+  hooks tried to inject. The helper now takes the event name and every
+  caller passes its own (`SessionStart` / `UserPromptSubmit` / `PostToolUse`).
+
 ## [1.2.0] — 2026-05-01
 
 Research-paper-driven detector update. Implements operational findings from

hooks/scripts/lib.mjs

@@ -289,10 +289,11 @@ export function outputContinue() {
   process.stdout.write(JSON.stringify({ continue: true }) + '\n');
 }
 
-export function outputWithContext(message) {
+export function outputWithContext(message, hookEventName) {
   process.stdout.write(JSON.stringify({
     continue: true,
     hookSpecificOutput: {
+      hookEventName,
       additionalContext: message
     }
   }) + '\n');

hooks/scripts/prompt-analyzer.mjs

@@ -487,7 +487,7 @@ if (warnings.length > 0) {
     const freshState = readState();
     freshState.last_warning_epoch = nowEpoch();
     writeState(freshState);
-    outputWithContext(warnings.join(' '));
+    outputWithContext(warnings.join(' '), 'UserPromptSubmit');
   } else {
     outputContinue();
   }

hooks/scripts/session-start.mjs

@@ -93,4 +93,4 @@ if (recent.length >= TIER2_SESSION_THRESHOLD) {
   }
 }
 
-outputWithContext(msg);
+outputWithContext(msg, 'SessionStart');

hooks/scripts/tool-tracker.mjs

@@ -127,7 +127,7 @@ const late = isLateNight() ? ' Late-night session.' : '';
 // No warnings — just periodic reminder at modulo-25
 if (!level) {
   if (toolCount % 25 === 0) {
-    outputWithContext('REMINDER (Interaction Awareness): Check your next response against these rules — no unearned affirmations, no reformulating the user\'s words in stronger terms, no skipping counterarguments to stay agreeable. If you detect a reinforcement loop, scope escalation, or narrative crystallization: name it now.');
+    outputWithContext('REMINDER (Interaction Awareness): Check your next response against these rules — no unearned affirmations, no reformulating the user\'s words in stronger terms, no skipping counterarguments to stay agreeable. If you detect a reinforcement loop, scope escalation, or narrative crystallization: name it now.', 'PostToolUse');
   } else {
     outputContinue();
   }
@@ -141,7 +141,7 @@ const elapsed = nowTs - lastWarning;
 if (lastWarning > 0 && elapsed < cooldown) {
   // Still in cooldown — send periodic reminder instead if at modulo-25
   if (toolCount % 25 === 0) {
-    outputWithContext('REMINDER (Interaction Awareness): Check your next response against these rules — no unearned affirmations, no reformulating the user\'s words in stronger terms, no skipping counterarguments to stay agreeable.');
+    outputWithContext('REMINDER (Interaction Awareness): Check your next response against these rules — no unearned affirmations, no reformulating the user\'s words in stronger terms, no skipping counterarguments to stay agreeable.', 'PostToolUse');
   } else {
     outputContinue();
   }
@@ -163,4 +163,4 @@ state = readState();
 state.last_warning_epoch = nowTs;
 writeState(state);
 
-outputWithContext(warning);
+outputWithContext(warning, 'PostToolUse');

tests/prompt-analyzer.test.mjs

@@ -273,6 +273,7 @@ describe('thresholds and cooldowns', () => {
     dir = setupTestDir();
     createStateFile(dir, 'p1', { ...freshState(), dep_flags: 1 });
     const out = runHook('prompt-analyzer.mjs', { session_id: 'p1', prompt: 'tell me what to do' }, dir);
+    assert.equal(out.hookSpecificOutput?.hookEventName, 'UserPromptSubmit');
     assert.ok(out.hookSpecificOutput?.additionalContext?.includes('Dependency language noticed'));
   });
 

tests/session-start.test.mjs

@@ -12,6 +12,7 @@ describe('session-start', () => {
     dir = setupTestDir();
     const out = runHook('session-start.mjs', { session_id: 's1', cwd: '/tmp' }, dir);
     assert.equal(out.continue, true);
+    assert.equal(out.hookSpecificOutput.hookEventName, 'SessionStart');
     assert.ok(out.hookSpecificOutput.additionalContext.includes('Interaction Awareness is active'));
     const state = readState(dir, 's1');
     assert.ok(state);

tests/tool-tracker.test.mjs

@@ -74,6 +74,7 @@ describe('tool-tracker', () => {
     dir = setupTestDir();
     createStateFile(dir, 't6', freshState({ tool_count: 24 }));
     const out = runHook('tool-tracker.mjs', { session_id: 't6', tool_name: 'Read' }, dir);
+    assert.equal(out.hookSpecificOutput?.hookEventName, 'PostToolUse');
     assert.ok(out.hookSpecificOutput?.additionalContext?.includes('REMINDER'));
   });