diff --git a/packages/core/src/__tests__/builtin-workflows.test.ts b/packages/core/src/__tests__/builtin-workflows.test.ts
index ecc49eda94..14bbbfb57f 100644
--- a/packages/core/src/__tests__/builtin-workflows.test.ts
+++ b/packages/core/src/__tests__/builtin-workflows.test.ts
@@ -393,6 +393,26 @@ describe("built-in workflows", () => {
     expect(ids.indexOf("merge")).toBeLessThan(ids.indexOf("document"));
   });
 
+  it("compound-engineering runs plan/code-review/document in coding mode and carries skillName onto compiled steps (U1/U4)", () => {
+    const ce = getBuiltinWorkflow("builtin:compound-engineering")!;
+    const byId = (id: string) => ce.ir.nodes.find((n) => n.id === id);
+    // U4: fan-out steps (plan, code-review) need coding so fn_spawn_agent is
+    // available for persona fan-out; document needs coding to WRITE docs/solutions.
+    expect(byId("plan")?.config?.toolMode).toBe("coding");
+    expect(byId("code-review")?.config?.toolMode).toBe("coding");
+    expect(byId("document")?.config?.toolMode).toBe("coding");
+    // U1: the compiler carries each node's skillName onto the materialized step so
+    // the step session can actually LOAD the skill (not just name it in prompt text).
+    const steps = compileWorkflowToSteps(ce.ir);
+    const plan = steps.find((s) => s.name === "Plan");
+    expect(plan?.skillName).toBe("compound-engineering:ce-plan");
+    expect(plan?.toolMode).toBe("coding");
+    const codeReview = steps.find((s) => s.skillName === "compound-engineering:ce-code-review");
+    expect(codeReview?.toolMode).toBe("coding");
+    const document = steps.find((s) => s.skillName === "compound-engineering:ce-compound");
+    expect(document?.toolMode).toBe("coding");
+  });
+
   describe("store integration", () => {
     const harness = createTaskStoreTestHarness();
     let store: ReturnType<typeof harness.store>;
diff --git a/packages/core/src/builtin-workflows.ts b/packages/core/src/builtin-workflows.ts
index 26b0562cfd..936c33f403 100644
--- a/packages/core/src/builtin-workflows.ts
+++ b/packages/core/src/builtin-workflows.ts
@@ -187,6 +187,10 @@ export const BUILTIN_WORKFLOWS: WorkflowDefinition[] = [
           name: "Plan",
           executor: "skill",
           skillName: "compound-engineering:ce-plan",
+          // Coding mode so ce-plan can fan out to its research subagents via
+          // fn_spawn_agent (registered only for coding-mode steps). It is not
+          // meant to write — see the accepted write-capability posture (Risk-1).
+          toolMode: "coding",
           prompt: "Produce a short implementation plan for this task before any code is written.",
         },
       },
@@ -213,6 +217,10 @@ export const BUILTIN_WORKFLOWS: WorkflowDefinition[] = [
           executor: "skill",
           skillName: "compound-engineering:ce-code-review",
           gateMode: "gate",
+          // Coding mode so ce-code-review can fan out to its reviewer-persona
+          // subagents via fn_spawn_agent. As a gate step it still emits the
+          // verdict JSON (KTD-6); it is not meant to write the tree (Risk-1).
+          toolMode: "coding",
           prompt: "Run a structured code review of the changes. Block merge on P0/P1 findings.",
         },
       },
@@ -253,6 +261,9 @@ export const BUILTIN_WORKFLOWS: WorkflowDefinition[] = [
           name: "Document learnings",
           executor: "skill",
           skillName: "compound-engineering:ce-compound",
+          // Coding mode so ce-compound can WRITE the learning doc into
+          // docs/solutions (readonly would strip write tools).
+          toolMode: "coding",
           prompt: "Capture any reusable learnings from this task into docs/solutions.",
         },
       },