fix: resolve publish blockers for v3.7.4→v3.8.0 release

- Fix #1991 crash: optional chaining for task-history sessionID access
- Fix #1992 think-mode: add antigravity entries to HIGH_VARIANT_MAP
- Fix #1949 Copilot premium misattribution: use createInternalAgentTextPart
- Fix #1982 load_skills: pass directory to discoverSkills for project-level skills
- Fix command priority: sort scopePriority before .find(), project-first return
- Fix Google provider transform: apply in userFallbackModels path
- Fix ralph-loop TUI: optional chaining for event handler
- Fix runtime-fallback: unify dual fallback engines, remove HTTP 400 from retry,
  fix pendingFallbackModel stuck state, add priority gate to skip model-fallback
  when runtime-fallback is active
- Fix Prometheus task system: exempt from todowrite/todoread deny
- Fix background_output: default full_session to true
- Remove orphan hooks: hashline-edit-diff-enhancer (redundant with hashline_edit
  built-in diff), task-reminder (dead code)
- Remove orphan config entries: 3 stale hook names from Zod schema
- Fix disabled_hooks schema: accept arbitrary strings for forward compatibility
- Register json-error-recovery hook in tool-guard pipeline
- Add disabled_hooks gating for question-label-truncator, task-resume-info,
  claude-code-hooks
- Update test expectations to match new behavior

src/plugin-handlers/config-handler.test.ts

@@ -1157,13 +1157,15 @@ describe("config-handler plugin loading error boundary (#1559)", () => {
 })
 
 describe("per-agent todowrite/todoread deny when task_system enabled", () => {
-  const PRIMARY_AGENTS = [
+  const AGENTS_WITH_TODO_DENY = new Set([
     getAgentDisplayName("sisyphus"),
     getAgentDisplayName("hephaestus"),
     getAgentDisplayName("atlas"),
+  ])
+  const AGENTS_WITHOUT_TODO_DENY = new Set([
     getAgentDisplayName("prometheus"),
     getAgentDisplayName("sisyphus-junior"),
-  ]
+  ])
 
   test("denies todowrite and todoread for primary agents when task_system is enabled", async () => {
     //#given
@@ -1200,10 +1202,14 @@ describe("per-agent todowrite/todoread deny when task_system enabled", () => {
 
     //#then
     const agentResult = config.agent as Record<string, { permission?: Record<string, unknown> }>
-    for (const agentName of PRIMARY_AGENTS) {
+    for (const agentName of AGENTS_WITH_TODO_DENY) {
       expect(agentResult[agentName]?.permission?.todowrite).toBe("deny")
       expect(agentResult[agentName]?.permission?.todoread).toBe("deny")
     }
+    for (const agentName of AGENTS_WITHOUT_TODO_DENY) {
+      expect(agentResult[agentName]?.permission?.todowrite).toBeUndefined()
+      expect(agentResult[agentName]?.permission?.todoread).toBeUndefined()
+    }
   })
 
   test("does not deny todowrite/todoread when task_system is disabled", async () => {