fix(atlas,todo-continuation): strip ZWSP sort prefix before promptAsync agent

Both injectors call resolveRegisteredAgentName, which returns the
registered alias verbatim. OpenCode TUI registers agent names with
leading zero-width characters (U+200B) for sort ordering, so that
alias can be e.g. "\u200B\u200BAtlas - Plan Executor". Passing it
directly to promptAsync produces "Agent not found" because the
OpenCode SDK does an exact match against its canonical display
name registry.

Strip the ZWSP sort prefix on the resolved name before sending it
to promptAsync in:
- src/hooks/atlas/boulder-continuation-injector.ts
- src/hooks/todo-continuation-enforcer/continuation-injection.ts

Add regression tests asserting promptAsync receives the canonical
display name (no \u200B) even when the registered alias carries
a ZWSP sort prefix. Same root cause class as #3494 / #3547. Tests
were RED on dev before the fix and GREEN after.

src/hooks/atlas/boulder-continuation-injector.ts

@@ -3,6 +3,7 @@ import {
   isAgentRegistered,
   resolveRegisteredAgentName,
 } from "../../features/claude-code-session-state"
+import { stripAgentListSortPrefix } from "../../shared/agent-display-names"
 import { log } from "../../shared/logger"
 import { createInternalAgentContinuationTextPart, resolveInheritedPromptTools } from "../../shared"
 import { promptAsyncAfterSessionIdle } from "../shared/prompt-async-gate"
@@ -67,9 +68,10 @@ export async function injectBoulderContinuation(input: {
 		`\n\n[Status: ${total - remaining}/${total} completed, ${remaining} remaining]` +
 		preferredSessionContext +
 		worktreeContext
-	const continuationAgent = resolveRegisteredAgentName(
+	const resolvedContinuationAgent = resolveRegisteredAgentName(
 		agent ?? (isAgentRegistered("atlas") ? "atlas" : undefined),
 	)
+	const continuationAgent = resolvedContinuationAgent ? stripAgentListSortPrefix(resolvedContinuationAgent) : resolvedContinuationAgent
 
 	if (!continuationAgent || !isAgentRegistered(continuationAgent)) {
 		log(`[${HOOK_NAME}] Skipped injection: continuation agent unavailable`, {

src/hooks/atlas/index.test.ts

@@ -2070,6 +2070,39 @@ session_id: ses_untrusted_999
       expect(callArgs.body.agent).not.toBe("atlas")
     })
 
+    test("#given boulder agent registered with ZWSP sort prefix #when continuation injects #then promptAsync receives display name without ZWSP", async () => {
+      // given - OpenCode TUI registers agent names with leading ZWSP for sort ordering
+      const planPath = join(TEST_DIR, "test-plan.md")
+      writeFileSync(planPath, "# Plan\n- [ ] Task 1\n- [ ] Task 2")
+
+      const state: BoulderState = {
+        active_plan: planPath,
+        started_at: "2026-01-02T10:00:00Z",
+        session_ids: [MAIN_SESSION_ID],
+        plan_name: "test-plan",
+        agent: "\u200B\u200BAtlas - Plan Executor",
+      }
+      writeBoulderState(TEST_DIR, state)
+      registerAgentName("\u200B\u200BAtlas - Plan Executor")
+
+      const mockInput = createMockPluginInput()
+      const hook = createTestAtlasHook(mockInput)
+
+      // when
+      await hook.handler({
+        event: {
+          type: "session.idle",
+          properties: { sessionID: MAIN_SESSION_ID },
+        },
+      })
+
+      // then
+      expect(mockInput._promptMock).toHaveBeenCalled()
+      const callArgs = mockInput._promptMock.mock.calls[0][0]
+      expect(callArgs.body.agent).toBe("Atlas - Plan Executor")
+      expect(callArgs.body.agent).not.toContain("\u200B")
+    })
+
     test("should debounce rapid continuation injections (prevent infinite loop)", async () => {
       // given - boulder state with incomplete plan
       const planPath = join(TEST_DIR, "test-plan.md")