fix: regenerate pi-claude-cli MCP config per session and auto-sync skill tools

The MCP config was generated lazily once and locked, so engine session-scoped
tools (fn_review_spec, fn_review_step) never reached the Claude CLI subprocess
and triage/executor sessions failed with "unknown tool" errors. Now the config
is hashed per call and rewritten when the tool set changes.

Also adds scripts/sync-fusion-skill-tools.mjs to regenerate the SKILL.md
tool-categories block from extension.ts at build time, with a --check mode
wired into skill-sync tests so drift fails CI.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/pi-claude-cli/src/__tests__/mcp-config.test.ts

@@ -269,4 +269,26 @@ describe("writeMcpConfig", () => {
     expect(result).toMatch(/pi-claude-mcp-config/);
     expect(result).toMatch(/\.json$/);
   });
+
+  it("includes cacheKey in filenames when provided so distinct tool sets do not collide", () => {
+    const toolDefs: McpToolDef[] = [
+      {
+        name: "search",
+        description: "Search",
+        inputSchema: { type: "object" },
+      },
+    ];
+
+    const pathA = writeMcpConfig(toolDefs, "aaaaaaaaaaaa");
+    const pathB = writeMcpConfig(toolDefs, "bbbbbbbbbbbb");
+
+    expect(pathA).toContain("aaaaaaaaaaaa");
+    expect(pathB).toContain("bbbbbbbbbbbb");
+    expect(pathA).not.toBe(pathB);
+
+    const schemaPathA = mocks.writeFileSync.mock.calls[0][0];
+    const schemaPathB = mocks.writeFileSync.mock.calls[2][0];
+    expect(schemaPathA).toContain("aaaaaaaaaaaa");
+    expect(schemaPathB).toContain("bbbbbbbbbbbb");
+  });
 });

packages/pi-claude-cli/src/mcp-config.ts

@@ -75,13 +75,21 @@ export function getCustomToolDefs(pi: PiInstance): McpToolDef[] {
  * 2. Config file: MCP config pointing to the schema-only server
  *
  * @param toolDefs - Array of custom tool definitions
+ * @param cacheKey - Optional suffix appended to filenames so that distinct
+ *   tool sets (e.g. session-scoped tool registrations) get distinct files
+ *   and don't race on a single shared path.
  * @returns Path to the MCP config file
  */
-export function writeMcpConfig(toolDefs: McpToolDef[]): string {
+export function writeMcpConfig(
+  toolDefs: McpToolDef[],
+  cacheKey?: string,
+): string {
+  const suffix = cacheKey ? `${process.pid}-${cacheKey}` : `${process.pid}`;
+
   // Write tool schemas to temp file
   const schemaFilePath = join(
     tmpdir(),
-    `pi-claude-mcp-schemas-${process.pid}.json`,
+    `pi-claude-mcp-schemas-${suffix}.json`,
   );
   writeFileSync(schemaFilePath, JSON.stringify(toolDefs));
 
@@ -103,7 +111,7 @@ export function writeMcpConfig(toolDefs: McpToolDef[]): string {
   // Write config to temp file
   const configFilePath = join(
     tmpdir(),
-    `pi-claude-mcp-config-${process.pid}.json`,
+    `pi-claude-mcp-config-${suffix}.json`,
   );
   writeFileSync(configFilePath, JSON.stringify(config));