diff --git a/desktop/scripts/check-file-sizes.mjs b/desktop/scripts/check-file-sizes.mjs
index 1af584877..966ece631 100644
--- a/desktop/scripts/check-file-sizes.mjs
+++ b/desktop/scripts/check-file-sizes.mjs
@@ -337,7 +337,7 @@ const overrides = new Map([
   // +29: rebase over main (#2680) — discover_acp_runtime_phase1 extracted
   // helper + discover_acp_runtime_availability; both load-bearing for
   // post-install verification. Semantic composition with BYOH changes.
-  ["src-tauri/src/managed_agents/discovery.rs", 1706],
+  ["src-tauri/src/managed_agents/discovery.rs", 1715],
   // BYOH — save_custom_harness_to_dir (backup-swap atomic write) + save_and_warm /
   // delete_and_warm (persist-mutex serialization for concurrent-safe registry
   // refresh, B-6). Also: id/collision/load/registry tests (from the file base) +
diff --git a/desktop/src-tauri/src/managed_agents/discovery.rs b/desktop/src-tauri/src/managed_agents/discovery.rs
index a6d419cfd..10102ea8b 100644
--- a/desktop/src-tauri/src/managed_agents/discovery.rs
+++ b/desktop/src-tauri/src/managed_agents/discovery.rs
@@ -1440,7 +1440,14 @@ const PRESET_HARNESSES: &[PresetHarness] = &[
         command: "openclaw",
         args: &["acp"],
         install_instructions_url: "https://docs.openclaw.ai/start/getting-started",
-        install_hint: "Install OpenClaw: npm install -g openclaw@latest.",
+        install_hint: "Install OpenClaw: npm install -g openclaw@latest.\n\n\
+            ⚠️  Execution-locus note: `openclaw acp` runs tools inside the \
+            OpenClaw Gateway daemon, not in the Desktop process. \
+            Desktop-injected BUZZ_* env vars are visible to the `openclaw` \
+            harness process itself, but do NOT automatically reach the \
+            Gateway's execution environment. If your tools or agent logic \
+            needs BUZZ_* credentials at execution time, set them on the \
+            Gateway's own environment separately.",
     },
 ];
 
diff --git a/desktop/src/app/postOnboardingNav.test.mjs b/desktop/src/app/postOnboardingNav.test.mjs
new file mode 100644
index 000000000..2be2eab95
--- /dev/null
+++ b/desktop/src/app/postOnboardingNav.test.mjs
@@ -0,0 +1,123 @@
+/**
+ * Tests for the post-onboarding navigation contract (Thufir F8).
+ *
+ * When the user clicks "Set up agents" during machine onboarding,
+ * MachineOnboardingFlow calls complete() then navigateAfterComplete({to, search}).
+ * App.tsx records the pending nav and fires it only when machine.stage === "ready"
+ * (i.e. once RouterProvider is mounted), never before.
+ *
+ * These are pure-logic tests — they simulate the App.tsx useEffect predicate
+ * directly. No React rendering needed; the behavior under test is:
+ *   pendingNav × stage → navigate() call count.
+ */
+import assert from "node:assert/strict";
+import test from "node:test";
+
+// ── Simulate the App.tsx postOnboardingNav useEffect logic ──────────────────
+//
+// The production code:
+//   useEffect(() => {
+//     if (machine.stage === "ready" && postOnboardingNav) {
+//       void router.navigate({ to: postOnboardingNav.to, search: ... });
+//       setPostOnboardingNav(null);
+//     }
+//   }, [machine.stage, postOnboardingNav]);
+//
+// We simulate this as a pure function and drive it through stage transitions.
+
+function runEffect(stage, nav, navigate) {
+  if (stage === "ready" && nav !== null) {
+    navigate({ to: nav.to, search: nav.search ?? {} });
+    return null; // cleared
+  }
+  return nav; // unchanged
+}
+
+test("navigate does not fire before stage reaches ready", () => {
+  const calls = [];
+  const navigate = (args) => calls.push(args);
+
+  const nav = { to: "/settings", search: { section: "agents" } };
+
+  // Drive through non-ready stages — navigate must not fire.
+  for (const stage of ["loading", "onboarding", "blocking"]) {
+    runEffect(stage, nav, navigate);
+  }
+
+  assert.equal(calls.length, 0, "navigate must not be called before ready");
+});
+
+test("navigate fires exactly once when stage transitions to ready", () => {
+  const calls = [];
+  const navigate = (args) => calls.push(args);
+
+  const nav = { to: "/settings", search: { section: "agents" } };
+
+  // Pre-ready stages — no call.
+  let pending = nav;
+  pending = runEffect("onboarding", pending, navigate);
+
+  // Stage reaches ready — navigate fires once.
+  pending = runEffect("ready", pending, navigate);
+
+  assert.equal(calls.length, 1, "navigate must fire exactly once on ready");
+  assert.equal(calls[0].to, "/settings");
+  assert.deepStrictEqual(calls[0].search, { section: "agents" });
+});
+
+test("navigate does not fire again after nav is cleared", () => {
+  const calls = [];
+  const navigate = (args) => calls.push(args);
+
+  const nav = { to: "/settings", search: { section: "agents" } };
+  let pending = nav;
+
+  // First ready transition fires and clears.
+  pending = runEffect("ready", pending, navigate);
+  assert.equal(calls.length, 1);
+  assert.equal(pending, null, "pending nav must be cleared after firing");
+
+  // Re-running the effect with null nav must not fire again.
+  pending = runEffect("ready", pending, navigate);
+  assert.equal(
+    calls.length,
+    1,
+    "navigate must not fire again after being cleared",
+  );
+});
+
+test("navigate fires immediately if nav is set while already ready", () => {
+  // Edge case: nav arrives after the machine is already ready (e.g. hot reload).
+  const calls = [];
+  const navigate = (args) => calls.push(args);
+
+  const nav = { to: "/settings", search: { section: "agents" } };
+
+  // Start with no pending nav while ready.
+  let pending = runEffect("ready", null, navigate);
+  assert.equal(calls.length, 0, "no nav pending → no call");
+
+  // Nav arrives (complete() called while already ready).
+  pending = runEffect("ready", nav, navigate);
+  assert.equal(calls.length, 1, "nav must fire immediately when already ready");
+  assert.equal(pending, null);
+});
+
+test("navigate intent carries exact to and search from navigateToAgentSettings", () => {
+  // Verifies the specific shape emitted by MachineOnboardingFlow's
+  // navigateToAgentSettings action: { to: '/settings', search: { section: 'agents' } }
+  const calls = [];
+  const navigate = (args) => calls.push(args);
+
+  // Simulate MachineOnboardingFlow calling navigateAfterComplete.
+  const nav = { to: "/settings", search: { section: "agents" } };
+  runEffect("ready", nav, navigate);
+
+  assert.equal(calls.length, 1);
+  assert.equal(calls[0].to, "/settings", "must navigate to /settings");
+  assert.equal(
+    calls[0].search.section,
+    "agents",
+    "must include section=agents",
+  );
+});
diff --git a/desktop/src/testing/e2eBridge.ts b/desktop/src/testing/e2eBridge.ts
index 96dcd8ba5..d685221e2 100644
--- a/desktop/src/testing/e2eBridge.ts
+++ b/desktop/src/testing/e2eBridge.ts
@@ -3,6 +3,11 @@ import { mockIPC, mockWindows } from "@tauri-apps/api/mocks";
 import { decode } from "nostr-tools/nip19";
 import { finalizeEvent, getPublicKey } from "nostr-tools/pure";
 import { parse as yamlParse } from "yaml";
+import {
+  mockCustomHarnesses,
+  handleSaveCustomHarness,
+  handleDeleteCustomHarness,
+} from "./e2eBridgeCustomHarnesses.ts";
 
 import { relayClient } from "@/shared/api/relayClient";
 import type { ConnectionState } from "@/shared/api/relayClientShared";
@@ -7039,7 +7044,10 @@ async function handleDiscoverAcpRuntimes(
       login_hint: undefined,
     },
   ];
-  return defaultCatalog.map(withMockRuntimeConfigMetadata);
+  return [
+    ...defaultCatalog.map(withMockRuntimeConfigMetadata),
+    ...Array.from(mockCustomHarnesses.values()),
+  ];
 }
 
 async function handleDiscoverAcpAuthMethods(
@@ -10008,6 +10016,14 @@ export function maybeInstallE2eTauriMocks() {
         return activeConfig?.mock?.relayRequiresMembership ?? false;
       case "discover_acp_providers":
         return handleDiscoverAcpRuntimes(activeConfig);
+      case "save_custom_harness":
+        return handleSaveCustomHarness(
+          payload as Parameters<typeof handleSaveCustomHarness>[0],
+        );
+      case "delete_custom_harness":
+        return handleDeleteCustomHarness(
+          payload as Parameters<typeof handleDeleteCustomHarness>[0],
+        );
       case "discover_acp_auth_methods":
         return handleDiscoverAcpAuthMethods(
           payload as { runtimeId?: string },
diff --git a/desktop/src/testing/e2eBridgeCustomHarnesses.test.mjs b/desktop/src/testing/e2eBridgeCustomHarnesses.test.mjs
new file mode 100644
index 000000000..795b04c3d
--- /dev/null
+++ b/desktop/src/testing/e2eBridgeCustomHarnesses.test.mjs
@@ -0,0 +1,155 @@
+/**
+ * Unit tests for the e2eBridge custom harness handlers (C-10).
+ *
+ * Tests are imported directly from the extracted e2eBridgeCustomHarnesses.ts
+ * module — no Tauri mock or browser environment needed — to prove:
+ *
+ *  1. save returns a catalog entry with source "custom" and correct fields
+ *  2. definition_env is preserved through save (non-empty env)
+ *  3. empty env produces absent definition_env (mirrors Rust BTreeMap serialization)
+ *  4. same-ID edit replaces the existing entry in the store (no duplicates)
+ *  5. rename (originalId ≠ id) removes the old key and inserts the new one
+ *  6. delete removes the entry from the store
+ *  7. delete is idempotent (not-found does not throw)
+ *  8. discover integration: saved harness appears in the discover result set
+ *     alongside the default catalog (verifies the Map is shared by reference)
+ */
+import assert from "node:assert/strict";
+import { beforeEach, describe, it } from "node:test";
+
+import {
+  mockCustomHarnesses,
+  resetMockCustomHarnesses,
+  handleSaveCustomHarness,
+  handleDeleteCustomHarness,
+} from "./e2eBridgeCustomHarnesses.ts";
+
+function makeArgs(overrides = {}) {
+  return {
+    definition: {
+      id: overrides.id ?? "test-harness",
+      label: overrides.label ?? "Test Harness",
+      command: overrides.command ?? "test-bin",
+      args: overrides.args ?? [],
+      env: overrides.env ?? {},
+      installInstructionsUrl: overrides.installInstructionsUrl ?? "",
+      installHint: overrides.installHint ?? "",
+    },
+    originalId: overrides.originalId ?? null,
+  };
+}
+
+// Reset the store before every test so tests are independent.
+beforeEach(() => resetMockCustomHarnesses());
+
+// ── save_custom_harness ───────────────────────────────────────────────────────
+
+describe("handleSaveCustomHarness", () => {
+  it("returns a catalog entry with source 'custom'", () => {
+    const entry = handleSaveCustomHarness(
+      makeArgs({ id: "my-rt", label: "My RT" }),
+    );
+    assert.equal(entry.id, "my-rt");
+    assert.equal(entry.label, "My RT");
+    assert.equal(entry.source, "custom");
+  });
+
+  it("stores the entry in mockCustomHarnesses", () => {
+    handleSaveCustomHarness(makeArgs({ id: "stored" }));
+    assert.ok(
+      mockCustomHarnesses.has("stored"),
+      "store must contain the saved id",
+    );
+  });
+
+  it("preserves non-empty definition_env", () => {
+    const env = { ANTHROPIC_API_KEY: "sk-test", MODEL: "claude-3" };
+    const entry = handleSaveCustomHarness(makeArgs({ id: "env-rt", env }));
+    assert.deepStrictEqual(entry.definition_env, env);
+    assert.deepStrictEqual(
+      mockCustomHarnesses.get("env-rt")?.definition_env,
+      env,
+    );
+  });
+
+  it("produces absent definition_env for empty env (mirrors Rust BTreeMap skip)", () => {
+    const entry = handleSaveCustomHarness(makeArgs({ id: "no-env", env: {} }));
+    assert.ok(
+      entry.definition_env === undefined || entry.definition_env === null,
+      "empty env must yield absent definition_env",
+    );
+  });
+
+  it("same-ID edit replaces entry — no duplicates in the store", () => {
+    handleSaveCustomHarness(makeArgs({ id: "dup", label: "V1" }));
+    handleSaveCustomHarness(
+      makeArgs({ id: "dup", label: "V2", originalId: "dup" }),
+    );
+    assert.equal(
+      mockCustomHarnesses.size,
+      1,
+      "same-ID edit must not duplicate store entries",
+    );
+    assert.equal(mockCustomHarnesses.get("dup")?.label, "V2");
+  });
+
+  it("rename removes old key and inserts new key", () => {
+    handleSaveCustomHarness(makeArgs({ id: "old-rt", label: "Old" }));
+    handleSaveCustomHarness(
+      makeArgs({ id: "new-rt", label: "New", originalId: "old-rt" }),
+    );
+    assert.ok(
+      !mockCustomHarnesses.has("old-rt"),
+      "old key must be removed on rename",
+    );
+    assert.ok(
+      mockCustomHarnesses.has("new-rt"),
+      "new key must be present after rename",
+    );
+    assert.equal(mockCustomHarnesses.get("new-rt")?.label, "New");
+  });
+});
+
+// ── delete_custom_harness ────────────────────────────────────────────────────
+
+describe("handleDeleteCustomHarness", () => {
+  it("removes an existing entry from the store", () => {
+    handleSaveCustomHarness(makeArgs({ id: "to-delete" }));
+    assert.ok(mockCustomHarnesses.has("to-delete"));
+
+    handleDeleteCustomHarness({ id: "to-delete" });
+    assert.ok(
+      !mockCustomHarnesses.has("to-delete"),
+      "entry must be removed after delete",
+    );
+  });
+
+  it("is idempotent — deleting non-existent id does not throw", () => {
+    assert.doesNotThrow(
+      () => handleDeleteCustomHarness({ id: "never-existed" }),
+      "delete of non-existent id must not throw",
+    );
+  });
+});
+
+// ── discover integration: store is shared by reference ───────────────────────
+
+describe("mockCustomHarnesses Map reference", () => {
+  it("handler writes are immediately visible to callers that read the exported Map", () => {
+    // e2eBridge.ts reads `Array.from(mockCustomHarnesses.values())` in
+    // handleDiscoverAcpRuntimes.  The exported Map is the same object by reference,
+    // so writes via the handler are visible to any reader of the Map.
+    assert.equal(
+      mockCustomHarnesses.size,
+      0,
+      "store must be empty after reset",
+    );
+
+    handleSaveCustomHarness(makeArgs({ id: "visible", label: "Visible" }));
+    assert.equal(mockCustomHarnesses.size, 1);
+
+    const [entry] = Array.from(mockCustomHarnesses.values());
+    assert.equal(entry.id, "visible");
+    assert.equal(entry.source, "custom");
+  });
+});
diff --git a/desktop/src/testing/e2eBridgeCustomHarnesses.ts b/desktop/src/testing/e2eBridgeCustomHarnesses.ts
new file mode 100644
index 000000000..c21e0a478
--- /dev/null
+++ b/desktop/src/testing/e2eBridgeCustomHarnesses.ts
@@ -0,0 +1,80 @@
+/**
+ * In-memory custom harness store for the e2e bridge.
+ *
+ * Extracted as a separate module so the handler logic can be unit-tested
+ * independently of the full e2eBridge.ts context (which requires a browser
+ * environment and full Playwright setup).
+ */
+import type { RawAcpRuntimeCatalogEntry } from "../shared/api/tauri.ts";
+
+/** In-memory store for custom harnesses saved via `save_custom_harness`. */
+export const mockCustomHarnesses = new Map<string, RawAcpRuntimeCatalogEntry>();
+
+/** Reset the store between tests. */
+export function resetMockCustomHarnesses(): void {
+  mockCustomHarnesses.clear();
+}
+
+/**
+ * Handle `save_custom_harness`.
+ *
+ * Persists the definition into `mockCustomHarnesses` so that the next
+ * `discover_acp_providers` call includes it. Mirrors the Rust command's
+ * return shape: an `AcpRuntimeCatalogEntry` for the saved harness.
+ */
+export function handleSaveCustomHarness(args: {
+  definition?: {
+    id?: string;
+    label?: string;
+    command?: string;
+    args?: string[];
+    env?: Record<string, string>;
+    installInstructionsUrl?: string;
+    installHint?: string;
+  };
+  originalId?: string | null;
+}): RawAcpRuntimeCatalogEntry {
+  const def = args.definition ?? {};
+  const id = def.id ?? "";
+  const originalId = args.originalId ?? null;
+
+  // On rename: remove the old entry so the old id is no longer in the catalog.
+  if (originalId && originalId !== id) {
+    mockCustomHarnesses.delete(originalId);
+  }
+
+  const entry: RawAcpRuntimeCatalogEntry = {
+    id,
+    label: def.label ?? id,
+    avatar_url: "",
+    availability: "not_installed", // PATH not probed in e2e mock
+    command: def.command ?? null,
+    binary_path: null,
+    default_args: def.args ?? [],
+    mcp_command: null,
+    install_hint: def.installHint ?? "",
+    install_instructions_url: def.installInstructionsUrl ?? "",
+    can_auto_install: false,
+    requires_external_cli: true,
+    underlying_cli_path: null,
+    node_required: false,
+    auth_status: { status: "not_applicable" },
+    source: "custom",
+    // Omit definition_env when the env map is empty — mirrors Rust's BTreeMap
+    // serialization which skips empty maps so the field is absent on the wire.
+    definition_env:
+      def.env && Object.keys(def.env).length > 0 ? def.env : undefined,
+    login_hint: undefined,
+  };
+  mockCustomHarnesses.set(id, entry);
+  return entry;
+}
+
+/**
+ * Handle `delete_custom_harness`.
+ * Removes the harness from the in-memory store. Idempotent (not-found is OK).
+ */
+export function handleDeleteCustomHarness(args: { id?: string }): void {
+  const id = args.id ?? "";
+  mockCustomHarnesses.delete(id);
+}
diff --git a/mobile/pubspec.lock b/mobile/pubspec.lock
index 64cc1becf..55185fc9c 100644
--- a/mobile/pubspec.lock
+++ b/mobile/pubspec.lock
@@ -820,10 +820,10 @@ packages:
     dependency: transitive
     description:
       name: meta
-      sha256: "1741988757a65eb6b36abe716829688cf01910bbf91c34354ff7ec1c3de2b349"
+      sha256: "23f08335362185a5ea2ad3a4e597f1375e78bce8a040df5c600c8d3552ef2394"
       url: "https://pub.dev"
     source: hosted
-    version: "1.18.0"
+    version: "1.17.0"
   mime:
     dependency: transitive
     description:
@@ -1273,26 +1273,26 @@ packages:
     dependency: transitive
     description:
       name: test
-      sha256: "8d9ceddbab833f180fbefed08afa76d7c03513dfdba87ffcec2718b02bbcbf20"
+      sha256: "280d6d890011ca966ad08df7e8a4ddfab0fb3aa49f96ed6de56e3521347a9ae7"
       url: "https://pub.dev"
     source: hosted
-    version: "1.31.0"
+    version: "1.30.0"
   test_api:
     dependency: transitive
     description:
       name: test_api
-      sha256: "949a932224383300f01be9221c39180316445ecb8e7547f70a41a35bf421fb9e"
+      sha256: "8161c84903fd860b26bfdefb7963b3f0b68fee7adea0f59ef805ecca346f0c7a"
       url: "https://pub.dev"
     source: hosted
-    version: "0.7.11"
+    version: "0.7.10"
   test_core:
     dependency: transitive
     description:
       name: test_core
-      sha256: "1991d4cfe85d5043241acac92962c3977c8d2f2add1ee73130c7b286417d1d34"
+      sha256: "0381bd1585d1a924763c308100f2138205252fb90c9d4eeaf28489ee65ccde51"
       url: "https://pub.dev"
     source: hosted
-    version: "0.6.17"
+    version: "0.6.16"
   tuple:
     dependency: transitive
     description: