refactor(FN-1317): rename remaining kb references to fn

- Update executor, triage, and merger prompt strings to identify the product as "fn"
- Align branch/worktree documentation examples with fusion/fn-* naming conventions
- Rename dashboard websocket attachment guard from __kbWebSocketsAttached to __fnWebSocketsAttached
- Refresh engine tests, dashboard utility comments, and TUI header text to remove stale kb wording

packages/engine/src/executor.ts

@@ -103,7 +103,7 @@ const reviewStepParams = Type.Object({
   ),
 });
 
-const EXECUTOR_SYSTEM_PROMPT = `You are a task execution agent for "kb", an AI-orchestrated task board.
+const EXECUTOR_SYSTEM_PROMPT = `You are a task execution agent for "fn", an AI-orchestrated task board.
 
 You are working in a git worktree isolated from the main branch. Your job is to implement the task described in the PROMPT.md specification you're given.
 
@@ -657,7 +657,7 @@ export class TaskExecutor {
    * than being named after the task ID. This decouples directory names from
    * tasks, enabling worktree reuse across dependency chains. When resuming
    * a task that already has `task.worktree` set, the existing path is used
-   * as-is. Branches remain task-scoped (`kb/{task-id}`).
+   * as-is. Branches remain task-scoped (`fusion/{task-id}`).
    */
   async execute(task: Task): Promise<void> {
     executorLog.log(`execute() called for ${task.id} (already executing=${this.executing.has(task.id)})`);
@@ -2068,9 +2068,9 @@ export class TaskExecutor {
   /**
    * Create a git worktree at `path` on a new branch.
    *
-   * @param branch — Branch name (e.g., `kb/kb-042`)
+   * @param branch — Branch name (e.g., `fusion/fn-042`)
    * @param path — Absolute worktree directory path
-   * @param startPoint — Optional git ref to branch from (e.g., `kb/kb-041`).
+   * @param startPoint — Optional git ref to branch from (e.g., `fusion/fn-041`).
    *   When provided, the worktree starts from that ref instead of HEAD.
    */
   /**
@@ -2357,7 +2357,7 @@ If issues are found that need attention, describe them clearly.`;
    * Create a git worktree with automatic recovery from conflicts.
    * Implements retry logic with exponential backoff for transient failures.
    * 
-   * @param branch - The branch name to create (e.g., "kb/kb-123")
+   * @param branch - The branch name to create (e.g., "fusion/fn-123")
    * @param path - The desired worktree path
    * @param taskId - The task ID for logging
    * @param startPoint - Optional base branch/commit for new branch

packages/engine/src/hybrid-executor.ts

@@ -71,7 +71,7 @@ export interface HybridExecutorOptions {
  * coordinates task execution across all registered projects, and enforces
  * global concurrency limits from CentralCore.
  *
- * This is the main entry point for multi-project task execution in kb. It sits
+ * This is the main entry point for multi-project task execution in fn. It sits
  * between CentralCore (project registry) and the individual ProjectRuntimes,
  * routing tasks to the appropriate runtime based on project configuration.
  *

packages/engine/src/merger.test.ts

@@ -246,7 +246,7 @@ describe("aiMergeTask — task.branch field", () => {
 
     const result = await aiMergeTask(store, "/tmp/root", "FN-050");
 
-    // Should use kb/fn-050-2, not kb/fn-050
+    // Should use fusion/fn-050-2, not fusion/fn-050
     expect(result.branch).toBe("fusion/fn-050-2");
 
     // Verify the suffixed branch was verified and deleted

packages/engine/src/merger.ts

@@ -594,7 +594,7 @@ and the bash tool returned exit code 0.
 The merge will only be completed if the build passes or no build command is configured.`;
   }
 
-  return `You are a merge agent for "kb", an AI-orchestrated task board.
+  return `You are a merge agent for "fn", an AI-orchestrated task board.
 
 Your job is to finalize a squash merge: resolve any conflicts and write a good commit message.
 All changes from the branch are squashed into a single commit.

packages/engine/src/pi.ts

@@ -1,5 +1,5 @@
 /**
- * Shared pi SDK setup for kb engine agents.
+ * Shared pi SDK setup for fn engine agents.
  *
  * Uses the user's existing pi auth (API keys / OAuth from ~/.pi/agent/auth.json).
  * Provides factory functions for creating triage and executor agent sessions.
@@ -254,7 +254,7 @@ async function registerExtensionProviders(cwd: string, modelRegistry: ModelRegis
 }
 
 /**
- * Create a pi agent session configured for kb.
+ * Create a pi agent session configured for fn.
  * Reuses the user's existing pi auth and model configuration.
  */
 export async function createKbAgent(options: AgentOptions): Promise<AgentResult> {

packages/engine/src/triage.ts

@@ -34,7 +34,7 @@ import {
   createTaskDocumentWriteTool,
 } from "./agent-tools.js";
 
-export const TRIAGE_SYSTEM_PROMPT = `You are a task specification agent for "kb", an AI-orchestrated task board.
+export const TRIAGE_SYSTEM_PROMPT = `You are a task specification agent for "fn", an AI-orchestrated task board.
 
 Your job: take a rough task description and produce a fully specified PROMPT.md that another AI agent can execute autonomously in a fresh context with zero memory of this conversation.
 

packages/engine/src/worktree-names.test.ts

@@ -8,7 +8,7 @@ describe("generateWorktreeName", () => {
   let tempDir: string;
 
   beforeEach(() => {
-    tempDir = mkdtempSync(join(tmpdir(), "kb-wt-test-"));
+    tempDir = mkdtempSync(join(tmpdir(), "fn-wt-test-"));
   });
 
   afterEach(() => {

packages/engine/src/worktree-pool.ts

@@ -112,11 +112,11 @@ export class WorktreePool {
    * 4. `git checkout -B <branchName> <startPoint>` — create/reset branch from start point
    *
    * Returns the actual branch name used. This may differ from `branchName`
-   * when conflict recovery generates a suffixed name (e.g., `kb/fn-042-2`).
+   * when conflict recovery generates a suffixed name (e.g., `fusion/fn-042-2`).
    *
    * @param worktreePath — Absolute path to the recycled worktree
-   * @param branchName — Branch name for the new task (e.g., `kb/kb-042`)
-   * @param startPoint — Git ref to branch from (e.g., `kb/kb-041`). Defaults to `main`.
+   * @param branchName — Branch name for the new task (e.g., `fusion/fn-042`)
+   * @param startPoint — Git ref to branch from (e.g., `fusion/fn-041`). Defaults to `main`.
    * @returns The actual branch name checked out in the worktree
    */
   prepareForTask(worktreePath: string, branchName: string, startPoint?: string): string {