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/tools/delegate-task/sync-prompt-sender.ts

@@ -7,6 +7,7 @@ import {
 import { formatDetailedError } from "./error-formatting"
 import { getAgentToolRestrictions } from "../../shared/agent-tool-restrictions"
 import { setSessionTools } from "../../shared/session-tools-store"
+import { createInternalAgentTextPart } from "../../shared/internal-initiator-marker"
 
 type SendSyncPromptDeps = {
   promptWithModelSuggestionRetry: typeof promptWithModelSuggestionRetry
@@ -56,7 +57,7 @@ export async function sendSyncPrompt(
       agent: input.agentToUse,
       system: input.systemContent,
       tools,
-      parts: [{ type: "text", text: input.args.prompt }],
+      parts: [createInternalAgentTextPart(input.args.prompt)],
       ...(input.categoryModel
         ? { model: { providerID: input.categoryModel.providerID, modelID: input.categoryModel.modelID } }
         : {}),