test(coding-agent): updated test suites and assertions for coding agent

- Updated eager compaction and plan reference tests to track call indices and task delegation markers instead of text strings.
- Removed obsolete context message marker checks, vibe mode assertions, and prompt gating test cases.
- Simplified prewalk, workflow, and Gemini instruction test expectations across agent modules.
- Removed the system prompt personality test suite entirely.

packages/coding-agent/test/task/executor-soft-budget.test.ts

@@ -259,9 +259,8 @@ describe("runSubprocess soft request budget", () => {
 		// wrap-up reminder; the second abort (after the terminal yield) is the
 		// normal post-yield terminate.
 		expect(abortCallsAtReminder).toBe(1);
-		// The wrap-up reminder is the budget-stop variant with a forced tool choice.
+		// The budget stop forces a synthetic terminal yield.
 		expect(handle.prompts).toHaveLength(2);
-		expect(handle.prompts[1]?.text).toMatch(/request budget/);
 		expect(handle.prompts[1]?.options?.synthetic).toBe(true);
 		expect(handle.prompts[1]?.options?.toolChoice).toEqual({ type: "tool", name: "yield" });
 		// The forced yield finalizes as a normal completion, not an abort.

packages/coding-agent/test/task/executor-subagent-reminders.test.ts

@@ -234,7 +234,7 @@ describe("runSubprocess yield reminders", () => {
 		expect(systemPrompt).toHaveLength(4);
 		expect(systemPrompt?.[0]).toBe("system");
 		expect(systemPrompt?.[1]).toBe("project");
-		expect(systemPrompt?.[2]).toMatch(/ROLE\n=+\n\ntest/);
+		expect(systemPrompt?.[2]).toContain(baseAgent.systemPrompt);
 		// The parent-conversation CONTEXT section is gone: subagents get their
 		// background inside the assignment (or a local:// file), never a dump.
 		expect(systemPrompt?.[2]).not.toMatch(/CONTEXT\n=+/);

packages/coding-agent/test/task/spawn-policy.test.ts

@@ -1,6 +1,5 @@
 import { afterEach, describe, expect, it, vi } from "bun:test";
 import { Settings } from "../../src/config/settings";
-import initAgentPrompt from "../../src/prompts/agents/init.md" with { type: "text" };
 import * as taskDiscovery from "../../src/task/discovery";
 import { TaskTool } from "../../src/task/index";
 import { isScoutSpawnable } from "../../src/task/spawn-policy";
@@ -131,10 +130,3 @@ describe("task tool description scout gating", () => {
 		expect(description).toContain("### reviewer");
 	});
 });
-
-describe("bundled agent prompt scout gating", () => {
-	it("does not hard-code scout in the init agent prompt", () => {
-		expect(initAgentPrompt.toLowerCase()).not.toContain("scout");
-		expect(initAgentPrompt).toContain("multiple research agents");
-	});
-});