@@ -30,3 +30,7 @@ subagents/
 
 # Working notes and design spikes — local only, never committed
 docs/plans/
+
+# Scratch repro tests — never committed
+__repro/
+**/__repro/
@@ -21,6 +21,7 @@ import type { MCPClient } from "../src/mcp/client.js";
 import { getSubAgentIdentity } from "../src/subagent/identity-context.js";
 import { createSubAgentSessionStore } from "../src/subagent/session-store.js";
 import { workerPermissionGate } from "../src/permission/reactor-authorize.js";
+import { getProcessWorkerGrantStore } from "../src/permission/worker-grant.js";
 import { gateAgentTools } from "../src/plugins/permission-plugin.js";
 
 const report =
@@ -69,6 +70,12 @@ async function withWorker(
       }),
   };
   try {
+    // Every probe reuses worker id "worker" in a fresh tmpdir, but denied-call
+    // grant envelopes live in a process-shared store keyed by that session id.
+    // A prior probe's pending envelope (same tool + empty args, other cwd)
+    // would veto this probe's call via the retry-from-another-directory
+    // blocker, so each probe starts from a clean store.
+    getProcessWorkerGrantStore().clear();
     await withMockedModuleDuring(
       import.meta.resolve("../src/session/assemble-runtime.js"),
       (real: typeof import("../src/session/assemble-runtime.js")) => ({
 
@@ -0,0 +1,182 @@
+/**
+ * CL-9704: Linear MCP discovery-to-invocation on the primary session.
+ *
+ * Regression lock for "discoverable but not callable": tool_search finds
+ * `mcp__linear__*`, and promote-on-execute must then commit a callable
+ * schema for exactly the called name and dispatch it — list_teams first,
+ * then save_issue. Search alone never promotes (the wire stays
+ * built-ins-only until a call), and promoting one name never implies its
+ * siblings: the primary session mounts MCP tools on demand, mirroring the
+ * worker requires_tools gate.
+ */
+
+import { afterEach, describe, expect, test } from "bun:test";
+import { mkdtempSync, rmSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+
+import {
+  installMcpConnectMock,
+  linearHttpMcpServer,
+  mcpTestPermissionGate,
+} from "../../testkit/mcp-connect-mock.js";
+
+const linearTools = [
+  {
+    name: "list_teams",
+    description: "List Linear teams",
+    inputSchema: { type: "object", properties: {}, required: [] },
+  },
+  {
+    name: "save_issue",
+    description: "Save a Linear issue",
+    inputSchema: {
+      type: "object",
+      properties: {
+        title: { type: "string" },
+        teamId: { type: "string" },
+      },
+      required: ["title"],
+    },
+  },
+];
+
+const mock = await installMcpConnectMock(
+  import.meta.resolve("../mcp/client.js"),
+  { initialTools: linearTools, toolCallResult: "linear-ok" },
+);
+
+const { createAgentToolset } = await import("./tools.js");
+const { createToolIndex, createToolSearchTool } =
+  await import("./tool-search.js");
+const { createAdvertisedToolset } =
+  await import("../session/assemble-runtime.js");
+
+const dirs: string[] = [];
+
+function tempDir(prefix: string): string {
+  const dir = mkdtempSync(join(tmpdir(), prefix));
+  dirs.push(dir);
+  return dir;
+}
+
+afterEach(() => {
+  mock.reset();
+  for (const dir of dirs.splice(0)) {
+    rmSync(dir, { recursive: true, force: true });
+  }
+});
+
+describe("CL-9704 linear MCP discovery-to-invocation", () => {
+  test("tool_search finds list_teams, promote-on-execute makes list_teams then save_issue callable", async () => {
+    const toolset = await createAgentToolset({
+      cwd: tempDir("corbits-cl9704-"),
+      permissionGate: mcpTestPermissionGate(),
+      onOperatorGate: async () => ({ kind: "cancel" }),
+      mcpServers: [linearHttpMcpServer],
+    });
+    try {
+      await toolset.connectMCP({
+        interactiveAuth: false,
+        onStatus: () => undefined,
+        onToolsChanged: () => undefined,
+      });
+
+      const registered = toolset.dynamicRunner
+        .currentDefinitions()
+        .map((d) => d.name);
+      expect(registered).toContain("mcp__linear__list_teams");
+      expect(registered).toContain("mcp__linear__save_issue");
+
+      // Primary-session promote-on-execute wiring (mirrors
+      // tui/runner/session.ts + tui/runner/exit.ts): the call gate keys off
+      // the advertised set, and the promoter declares exactly the called
+      // name, committing its schema onto the next infer's wire.
+      const advertised = createAdvertisedToolset({
+        sessionMode: "orchestrator",
+        toolAvailability: { languageServerAvailable: false },
+        getProvider: () => ({ providerName: "test", model: "test" }),
+      });
+      toolset.dynamicRunner.setCallGate(
+        (name) => advertised.isAdvertised(name),
+        { isActivated: (name) => advertised.activated.has(name) },
+      );
+      let wire: string[] = [];
+      toolset.setToolPromoter((names) => {
+        advertised.activated.activate(names);
+        if (advertised.flushPromotions()) {
+          wire = advertised
+            .computeAdvertised(toolset.dynamicRunner.currentDefinitions())
+            .map((d) => d.name);
+        }
+      });
+      const wireSchemas = (): Map<string, unknown> =>
+        new Map(
+          advertised
+            .computeAdvertised(toolset.dynamicRunner.currentDefinitions())
+            .map((d) => [d.name, d.inputSchema]),
+        );
+
+      const index = createToolIndex(() =>
+        toolset.dynamicRunner.currentDefinitions(),
+      );
+      const search = createToolSearchTool({
+        search: (query, limit) => index.search(query, limit),
+        lookup: (name) =>
+          toolset.dynamicRunner
+            .currentDefinitions()
+            .find((d) => d.name === name),
+      });
+      if (search.kind !== "string") throw new Error("expected string tool");
+
+      // Discovery: the card names list_teams with its description.
+      const card = await search.handler(
+        { query: "linear teams" },
+        new AbortController().signal,
+      );
+      expect(card).toContain("mcp__linear__list_teams");
+      expect(card).toContain("List Linear teams");
+
+      // Search alone promotes nothing: no Linear schema on the wire.
+      expect(wire).not.toContain("mcp__linear__list_teams");
+      expect(wire).not.toContain("mcp__linear__save_issue");
+
+      const run = (name: string, args: Record<string, unknown> = {}) =>
+        toolset.dynamicRunner.run(
+          { id: `call-${name}`, name, arguments: args },
+          new AbortController().signal,
+        );
+
+      // Invocation 1: list_teams dispatches and promotes only itself.
+      const listed = await run("mcp__linear__list_teams");
+      expect(listed.isError).toBeUndefined();
+      expect(listed.content).toContain("linear-ok");
+      expect(wire).toContain("mcp__linear__list_teams");
+      expect(wire).not.toContain("mcp__linear__save_issue");
+      expect(wireSchemas().get("mcp__linear__list_teams")).toEqual(
+        linearTools[0]?.inputSchema,
+      );
+
+      // Invocation 2: save_issue dispatches with its args after discovery.
+      const saved = await run("mcp__linear__save_issue", {
+        title: "hello",
+        teamId: "t1",
+      });
+      expect(saved.isError).toBeUndefined();
+      expect(saved.content).toContain("linear-ok");
+      expect(wire).toEqual(
+        expect.arrayContaining([
+          "mcp__linear__list_teams",
+          "mcp__linear__save_issue",
+        ]),
+      );
+      expect(mock.calls.map((c) => c.toolName)).toEqual([
+        "list_teams",
+        "save_issue",
+      ]);
+      expect(mock.calls[1]?.args).toEqual({ title: "hello", teamId: "t1" });
+    } finally {
+      await toolset.dispose();
+    }
+  });
+});
@@ -1,5 +1,6 @@
 import { describe, expect, test } from "bun:test";
 
+import { stringTool, type AgentTool } from "@intx/agent";
 import {
   createFleetMailbox,
   createSpawnAgentTool,
@@ -38,6 +39,13 @@ const FULL_MOUNT_PROFILE: AgentProfile = {
   systemPromptRole: "You do anything.",
 };
 
+// BUILD_TOOLS-like envelope: built-ins only, no MCP names.
+const BUILD_LIKE_PROFILE: AgentProfile = {
+  id: "build-worker",
+  systemPromptRole: "You build.",
+  capabilities: { mode: "allow", tools: ["read_file", "run_shell"] },
+};
+
 function makeDeps(
   run: (params: RunSubAgentParams) => Promise<RunSubAgentResult>,
   capturedTelemetry: TelemetryEvent[],
@@ -300,6 +308,156 @@ describe("spawn_agent requires_tools preflight", () => {
     expect(seenTier).toBe("leaf");
   });
 
+  test("mounted mcp__linear__ tool passes dispatch preflight under a built-ins-only allowlist", async () => {
+    const telemetry: TelemetryEvent[] = [];
+    let runCalled = false;
+    let seenRequires: readonly string[] | undefined;
+    const linearTool: AgentTool = stringTool({
+      definition: {
+        name: "mcp__linear__list_teams",
+        description: "Inherited Linear tool",
+        inputSchema: {},
+      },
+      handler: async () => "teams",
+    });
+    const base = makeDeps(async (params) => {
+      runCalled = true;
+      seenRequires = params.requiresTools;
+      return { report: "done" };
+    }, telemetry);
+    const deps: AgentFleetDeps = {
+      ...base,
+      profiles: [BUILD_LIKE_PROFILE],
+      inheritMcpTools: () => [linearTool],
+    };
+    const spawn = createSpawnAgentTool(deps);
+
+    const result = await callSpawn(spawn, {
+      description: "linear job",
+      prompt: "list teams",
+      agent: "build-worker",
+      requires_tools: ["mcp__linear__list_teams"],
+    });
+
+    expect(result.isError).not.toBe(true);
+    expect(runCalled).toBe(true);
+    const body = JSON.parse(result.content) as { agent_id: string };
+    expect(deps.sessions.get(body.agent_id)?.requiresTools).toEqual([
+      "mcp__linear__list_teams",
+    ]);
+    expect(seenRequires).toEqual(["mcp__linear__list_teams"]);
+  });
+
+  test("unmounted mcp__linear__ tool rejects dispatch preflight as unknown_tool with no run", async () => {
+    const telemetry: TelemetryEvent[] = [];
+    let runCalled = false;
+    const base = makeDeps(async () => {
+      runCalled = true;
+      return { report: "done" };
+    }, telemetry);
+    const deps: AgentFleetDeps = {
+      ...base,
+      profiles: [BUILD_LIKE_PROFILE],
+    };
+    const spawn = createSpawnAgentTool(deps);
+
+    const result = await callSpawn(spawn, {
+      description: "linear job",
+      prompt: "list teams",
+      agent: "build-worker",
+      requires_tools: ["mcp__linear__list_teams"],
+    });
+
+    expect(result.isError).toBe(true);
+    expect(result.content).toContain('unknown tool "mcp__linear__list_teams"');
+    expect(result.content).not.toContain("Did you mean");
+    expect(runCalled).toBe(false);
+    expect(deps.sessions.list()).toEqual([]);
+    expect(telemetry).toEqual([]);
+  });
+
+  test("requires_tools stamps only the requested live tool, never the inherited set", async () => {
+    const telemetry: TelemetryEvent[] = [];
+    let runCalled = false;
+    let seenRequires: readonly string[] | undefined;
+    const mcpTool = (name: string): AgentTool =>
+      stringTool({
+        definition: {
+          name,
+          description: `Inherited ${name}`,
+          inputSchema: {},
+        },
+        handler: async () => name,
+      });
+    const base = makeDeps(async (params) => {
+      runCalled = true;
+      seenRequires = params.requiresTools;
+      return { report: "done" };
+    }, telemetry);
+    const deps: AgentFleetDeps = {
+      ...base,
+      profiles: [BUILD_LIKE_PROFILE],
+      inheritMcpTools: () => [
+        mcpTool("mcp__linear__list_teams"),
+        mcpTool("mcp__linear__create_issue"),
+      ],
+    };
+    const spawn = createSpawnAgentTool(deps);
+
+    const result = await callSpawn(spawn, {
+      description: "linear job",
+      prompt: "list teams",
+      agent: "build-worker",
+      requires_tools: ["mcp__linear__list_teams"],
+    });
+
+    // On-demand: dispatch stamps exactly the requested live tool — the
+    // inherited sibling mounts only under its own stamp (run.ts drops it).
+    expect(result.isError).not.toBe(true);
+    expect(runCalled).toBe(true);
+    expect(seenRequires).toEqual(["mcp__linear__list_teams"]);
+  });
+
+  test("requires_tools naming a live and an unmounted mcp__ tool rejects the unmounted one with no run", async () => {
+    const telemetry: TelemetryEvent[] = [];
+    let runCalled = false;
+    const base = makeDeps(async () => {
+      runCalled = true;
+      return { report: "done" };
+    }, telemetry);
+    const deps: AgentFleetDeps = {
+      ...base,
+      profiles: [BUILD_LIKE_PROFILE],
+      inheritMcpTools: () => [
+        stringTool({
+          definition: {
+            name: "mcp__linear__list_teams",
+            description: "Inherited Linear tool",
+            inputSchema: {},
+          },
+          handler: async () => "teams",
+        }),
+      ],
+    };
+    const spawn = createSpawnAgentTool(deps);
+
+    const result = await callSpawn(spawn, {
+      description: "linear job",
+      prompt: "list teams and file",
+      agent: "build-worker",
+      requires_tools: ["mcp__linear__list_teams", "mcp__linear__create_issue"],
+    });
+
+    expect(result.isError).toBe(true);
+    expect(result.content).toContain(
+      'unknown tool "mcp__linear__create_issue"',
+    );
+    expect(result.content).not.toContain("Did you mean");
+    expect(runCalled).toBe(false);
+    expect(deps.sessions.list()).toEqual([]);
+    expect(telemetry).toEqual([]);
+  });
+
   test("whitespace-only requires_tools rejects fail-closed with no session, telemetry, or run", async () => {
     for (const requiresTools of [["   "], ["read_file", "  "]]) {
       const telemetry: TelemetryEvent[] = [];