fix(ralph-loop): send registered agent display name on continue

Continuation injector previously called normalizeAgentForPromptKey,
which collapsed agent inputs like "Sisyphus - Ultraworker" or
"sisyphus" down to the lowercase config key (e.g. "sisyphus").
OpenCode's promptAsync rejects that with "Agent not found", so the
ralph-loop continue prompt silently failed to dispatch on parent
sessions whose inherited message used a known display name.

Switch to normalizeAgentForPrompt and add a small wrapper that:
- preserves any agent string already in canonical " - " display form
  verbatim (covers ZWSP-prefixed inheritance and user-defined custom
  agents)
- otherwise normalizes config keys / legacy parenthesized names to the
  registered display name OpenCode expects.

Update the existing regression tests so that ZWSP-prefixed and clean
inherited agents both assert the registered display name reaches
promptAsync.

src/hooks/ralph-loop/continuation-prompt-injector.test.ts

@@ -59,7 +59,7 @@ describe("ralph-loop continuation prompt injector", () => {
     }
   })
 
-  test("#given inherited message agent has ZWSP prefix #when injecting continuation prompt #then promptAsync receives normalized agent", async () => {
+  test("#given inherited message agent has ZWSP prefix #when injecting continuation prompt #then promptAsync receives registered display agent", async () => {
     // given
     let promptBody: { agent?: string; noReply?: boolean } | undefined
     let promptPart:
@@ -103,14 +103,14 @@ describe("ralph-loop continuation prompt injector", () => {
     })
 
     // then
-    expect(promptBody?.agent).toBe("sisyphus")
+    expect(promptBody?.agent).toBe("Sisyphus - Ultraworker")
     expect(promptBody?.agent).not.toContain("\u200b")
     expect(promptBody?.noReply).toBeUndefined()
     expect(promptPart?.synthetic).toBe(true)
     expect(promptPart?.metadata?.compaction_continue).toBe(true)
   })
 
-  test("#given inherited message agent has no ZWSP prefix #when injecting continuation prompt #then promptAsync receives normalized agent", async () => {
+  test("#given inherited message agent has no ZWSP prefix #when injecting continuation prompt #then promptAsync receives registered display agent", async () => {
     // given
     let promptBody: { agent?: string } | undefined
     const ctx = {
@@ -136,7 +136,7 @@ describe("ralph-loop continuation prompt injector", () => {
     })
 
     // then
-    expect(promptBody?.agent).toBe("sisyphus")
+    expect(promptBody?.agent).toBe("Sisyphus - Ultraworker")
   })
 
   test("#given inherited message model includes variant #when injecting continuation prompt #then promptAsync receives variant as a top-level field", async () => {

src/hooks/ralph-loop/continuation-prompt-injector.ts

@@ -9,7 +9,7 @@ import {
 	normalizeSDKResponse,
 	resolveInheritedPromptTools,
 } from "../../shared"
-import { normalizeAgentForPromptKey } from "../../shared/agent-display-names"
+import { normalizeAgentForPrompt, stripAgentListSortPrefix } from "../../shared/agent-display-names"
 import { promptAsyncAfterSessionIdle } from "../shared/prompt-async-gate"
 
 type MessageInfo = {
@@ -60,6 +60,23 @@ function createPromptAsyncError(prefix: string, error: unknown): Error {
 	return new Error(`${prefix}: ${describePromptAsyncError(error)}`)
 }
 
+function normalizeInheritedAgentForPrompt(agent: string | undefined): string | undefined {
+	if (typeof agent !== "string") {
+		return undefined
+	}
+
+	const inheritedAgent = stripAgentListSortPrefix(agent).trim()
+	if (!inheritedAgent) {
+		return undefined
+	}
+
+	if (inheritedAgent.includes(" - ")) {
+		return inheritedAgent
+	}
+
+	return normalizeAgentForPrompt(inheritedAgent)
+}
+
 export async function injectContinuationPrompt(
 	ctx: PluginInput,
 	options: {
@@ -113,7 +130,7 @@ export async function injectContinuationPrompt(
 	}
 
 	const inheritedTools = resolveInheritedPromptTools(sourceSessionID, tools)
-	const cleanAgent = normalizeAgentForPromptKey(agent)
+	const cleanAgent = normalizeInheritedAgentForPrompt(agent)
 
 	const launchModel = model
 		? { providerID: model.providerID, modelID: model.modelID }