fix(FN-2392): normalize skill-facing tool references to fn_*

- Update Fusion skill docs, prompts, and capability references to use public fn_* tool names consistently
- Align engine system prompts and tool schemas for messaging/task actions with fn_send_message, fn_read_messages, fn_task_* naming
- Refresh related tests across CLI, engine, dashboard, and core to match normalized tool naming and behavior
- Add a patch changeset for @runfusion/fusion describing the skill-tool namespace normalization

packages/cli/skill/fusion/SKILL.md

@@ -21,6 +21,8 @@ Mission → Milestone → Slice → Feature → Task
 
 **Available tools:** Fusion registers tools via the pi extension (prefixed `fn_*`). No CLI commands or Bash needed — use the registered tools directly.
 
+**Naming boundary:** The published skill surface always uses `fn_*` tool names (for example `fn_task_create`, `fn_mission_create`). Internal engine runtime tools like `task_create`, `task_update`, `task_log`, and `task_done` are intentionally unprefixed and not part of this skill.
+
 **Tool categories:**
 - **Task tools** — `fn_task_create`, `fn_task_update`, `fn_task_list`, `fn_task_show`, `fn_task_attach`, `fn_task_pause`, `fn_task_unpause`, `fn_task_retry`, `fn_task_duplicate`, `fn_task_refine`, `fn_task_archive`, `fn_task_unarchive`, `fn_task_delete`, `fn_task_plan`
 - **GitHub tools** — `fn_task_import_github`, `fn_task_import_github_issue`, `fn_task_browse_github_issues`

packages/cli/skill/fusion/references/extension-tools.md

@@ -2,6 +2,8 @@
 
 All tools are registered via the pi extension. They are available in any pi agent session when the Fusion extension is installed.
 
+> Naming contract: all externally exposed Fusion extension tools are `fn_*` (for example `fn_task_create`). Internal engine/executor runtime tools (`task_create`, `task_update`, `task_log`, `task_done`, etc.) are separate and intentionally out of scope for this skill surface.
+
 ## Task Tools
 
 ### fn_task_create

packages/cli/skill/fusion/references/fusion-capabilities.md

@@ -7,6 +7,8 @@ Triage → Todo → In Progress → In Review → Done → Archived
 
 ## Pi Extension Tools (Available to Agents)
 
+All skill/extension tool invocations in this catalog use the public `fn_*` namespace. Engine runtime tools (for example `task_create`, `task_update`, `task_log`, `task_done`) are internal and intentionally not listed here.
+
 | Tool | Purpose |
 |------|---------|
 | `fn_task_create` | Create a new task in triage |

packages/cli/skill/fusion/workflows/specifications.md

@@ -5,6 +5,8 @@
 
 <objective>
 Guide the agent through creating well-specified tasks and organizing work using the mission hierarchy for complex multi-phase projects.
+
+All tool examples in this workflow intentionally use the public `fn_*` extension namespace.
 </objective>
 
 <process>

packages/cli/skill/fusion/workflows/task-management.md

@@ -5,6 +5,8 @@
 
 <objective>
 Guide the agent through creating, viewing, and managing tasks on the Fusion board using pi extension tools.
+
+Use only the public `fn_*` extension tools in this workflow. Do not substitute internal engine runtime tools like `task_create`, `task_update`, `task_log`, or `task_done`.
 </objective>
 
 <process>

packages/cli/src/__tests__/skill-sync.test.ts

@@ -1,6 +1,6 @@
 import { describe, it, expect } from "vitest";
-import { readFileSync, existsSync } from "node:fs";
-import { resolve, dirname } from "node:path";
+import { readFileSync, existsSync, readdirSync } from "node:fs";
+import { resolve, dirname, relative, join } from "node:path";
 import { fileURLToPath } from "node:url";
 
 const __dirname = dirname(fileURLToPath(import.meta.url));
@@ -52,6 +52,25 @@ function getCapabilitiesToolNames(): string[] {
   return matches.map((m) => m[1]).sort();
 }
 
+function collectMarkdownFiles(dir: string): string[] {
+  const files: string[] = [];
+  for (const entry of readdirSync(dir, { withFileTypes: true })) {
+    const fullPath = join(dir, entry.name);
+    if (entry.isDirectory()) {
+      files.push(...collectMarkdownFiles(fullPath));
+      continue;
+    }
+    if (entry.isFile() && entry.name.endsWith(".md")) {
+      files.push(fullPath);
+    }
+  }
+  return files.sort();
+}
+
+function escapeRegex(value: string): string {
+  return value.replace(/[.*+?^${}()|[\]\\]/g, "\\$&");
+}
+
 describe("Skill-Extension Sync", () => {
   it("skill directory structure exists", () => {
     expect(existsSync(resolve(skillDir, "SKILL.md"))).toBe(true);
@@ -105,6 +124,65 @@ describe("Skill-Extension Sync", () => {
     expect(missingFromCaps).toEqual([]);
   });
 
+  it("covers the full Fusion skill markdown surface", () => {
+    const markdownFiles = collectMarkdownFiles(skillDir).map((filePath) =>
+      relative(skillDir, filePath),
+    );
+
+    expect(markdownFiles).toEqual([
+      "SKILL.md",
+      "references/best-practices.md",
+      "references/cli-commands.md",
+      "references/extension-tools.md",
+      "references/fusion-capabilities.md",
+      "references/skill-patterns.md",
+      "references/task-structure.md",
+      "workflows/dashboard-cli.md",
+      "workflows/specifications.md",
+      "workflows/task-lifecycle.md",
+      "workflows/task-management.md",
+    ]);
+  });
+
+  it("enforces fn_* naming across extension + all skill markdown for public tools", () => {
+    const extensionTools = getExtensionToolNames();
+    const publicSuffixes = extensionTools.map((toolName) =>
+      toolName.replace(/^fn_/, ""),
+    );
+
+    // These names are intentionally unprefixed engine/runtime tools and are allowed
+    // to appear in docs that explain capability boundaries.
+    const allowedUnprefixedInternalTools = new Set([
+      "task_create",
+      "task_update",
+      "task_log",
+      "task_done",
+      "review_step",
+      "spawn_agent",
+    ]);
+
+    const forbiddenSuffixes = publicSuffixes.filter(
+      (suffix) => !allowedUnprefixedInternalTools.has(suffix),
+    );
+
+    const filesToScan = [extensionPath, ...collectMarkdownFiles(skillDir)];
+    const violations: string[] = [];
+
+    for (const filePath of filesToScan) {
+      const content = readFileSync(filePath, "utf-8");
+      const relativePath = relative(cliRoot, filePath);
+
+      for (const suffix of forbiddenSuffixes) {
+        const regex = new RegExp(`(?<!fn_)\\b${escapeRegex(suffix)}\\b`, "g");
+        if (regex.test(content)) {
+          violations.push(`${relativePath}: ${suffix}`);
+        }
+      }
+    }
+
+    expect(violations).toEqual([]);
+  });
+
   it("/fn command is documented in the skill", () => {
     const skillMd = readFileSync(resolve(skillDir, "SKILL.md"), "utf-8");
     expect(skillMd).toContain("/fn");