diff --git a/.superpowers/sdd/onboarding-cache-fix-report.md b/.superpowers/sdd/onboarding-cache-fix-report.md
new file mode 100644
index 00000000..1ff6448b
--- /dev/null
+++ b/.superpowers/sdd/onboarding-cache-fix-report.md
@@ -0,0 +1,152 @@
+# Onboarding cache identity final-review fix
+
+## Outcome
+
+- Status: `DONE_WITH_CONCERNS`
+- Base SHA: `308e5d532ae10846ef196cf21eea3efc49a843dd`
+- Commit: `fix: bind onboarding cache to profile identity`
+- Resulting commit SHA: reported in the task handoff. A Git commit cannot embed its own resulting SHA without changing that SHA.
+
+The onboarding cache now derives deterministic SHA-256 ready and pending versions from every
+profile field used by the route's completeness/generation decision. The database version contains
+no raw name, birth date/time, or location value. A ready value is accepted only for the current
+profile identity, a fresh pending value blocks only that same identity, and a completion can update
+the cache only while its exact pending identity still owns the row.
+
+The claim write compares both the observed old version and the observed
+`onboarding_generated_at`. The timestamp predicate preserves the existing two-minute TTL while
+ensuring concurrent reclaimers cannot both acquire an expired deterministic pending identity.
+
+The requested candidate-completion negative matrix exposed one real policy gap: the pure validator
+accepted any nonempty stored owner. It now receives the authenticated user ID and requires exact
+owner equality in addition to the route's owner-scoped query. No confidence, status, or billing
+policy changed.
+
+## Files
+
+- `frontend/src/app/api/onboarding/route.ts`
+- `frontend/src/lib/onboarding-cache-policy.ts`
+- `frontend/tests/onboarding-cache-policy.test.ts`
+- `frontend/src/app/api/birth-time-candidate-completion/route.ts`
+- `frontend/src/lib/birth-time-candidate-completion.ts`
+- `frontend/tests/birth-time-candidate-completion.test.ts`
+- `.superpowers/sdd/onboarding-cache-fix-report.md`
+
+Unrelated `.superpowers/sdd/task-1-report.md` and `.omo/` changes were preserved and excluded from
+the staged commit.
+
+## TDD evidence
+
+### RED — profile-aware cache policy
+
+The shell's bare `node` command first failed with exit 127, so it was not counted as behavioral
+evidence. Using the installed Node 24.14.0 runtime:
+
+```text
+/Users/jesse/.cache/codex-runtimes/codex-primary-runtime/dependencies/node/bin/node --test tests/onboarding-cache-policy.test.ts
+```
+
+Result before the policy module existed: exit 1, `ERR_MODULE_NOT_FOUND` for
+`src/lib/onboarding-cache-policy.ts`; 0 passed, 1 failed. The missing public policy seam was the
+expected RED.
+
+### RED — candidate owner matrix
+
+```text
+/Users/jesse/.cache/codex-runtimes/codex-primary-runtime/dependencies/node/bin/node --test tests/birth-time-candidate-completion.test.ts
+```
+
+Result before owner binding: exit 1; 13 passed, 2 failed. Both failures returned `"04:53"` instead
+of `null` for (1) a case owned by another user and (2) a request authenticated as another user.
+
+### GREEN — focused behavior
+
+```text
+/Users/jesse/.cache/codex-runtimes/codex-primary-runtime/dependencies/node/bin/node --test tests/onboarding-cache-policy.test.ts tests/birth-time-candidate-completion.test.ts
+```
+
+Result: exit 0; 20 passed, 0 failed. Coverage includes cached A to B, active-pending A to B, stale A
+completion after B claims, current ready/pending behavior, TTL reclaim, wrong case/owner, all three
+result-ID positions, missing winner/time, nonterminal action, and illegal status/action pairings.
+
+## Final verification
+
+Full frontend tests:
+
+```text
+/Users/jesse/.cache/codex-runtimes/codex-primary-runtime/dependencies/node/bin/node --test tests/*.test.ts
+```
+
+Result: exit 0; 444 passed, 0 failed.
+
+Changed-file ESLint:
+
+```text
+/Users/jesse/.cache/codex-runtimes/codex-primary-runtime/dependencies/node/bin/node node_modules/eslint/bin/eslint.js src/app/api/onboarding/route.ts src/lib/onboarding-cache-policy.ts tests/onboarding-cache-policy.test.ts src/app/api/birth-time-candidate-completion/route.ts src/lib/birth-time-candidate-completion.ts tests/birth-time-candidate-completion.test.ts
+```
+
+Result: exit 0; zero diagnostics.
+
+Production build with the repository's CI public placeholders and the webpack fallback:
+
+```text
+NEXT_PUBLIC_SUPABASE_URL=https://ci-placeholder.supabase.co NEXT_PUBLIC_SUPABASE_ANON_KEY=ci-placeholder PATH=/Users/jesse/.cache/codex-runtimes/codex-primary-runtime/dependencies/node/bin:$PATH ./node_modules/.bin/next build --webpack
+```
+
+Result: exit 0. Next 16.2.10 compiled successfully, finished TypeScript, generated 22/22 pages,
+and listed `/api/onboarding` and `/api/birth-time-candidate-completion` as dynamic routes.
+
+Direct TypeScript diagnostic:
+
+```text
+PATH=/Users/jesse/.cache/codex-runtimes/codex-primary-runtime/dependencies/node/bin:$PATH ./node_modules/.bin/tsc --noEmit
+```
+
+Result: exit 2 only for eight pre-existing ES2018 regexp-flag diagnostics in unrelated
+`tests/consultation-entrypoint.test.ts` and `tests/profile-persistence.test.ts`. No changed file was
+reported. The successful Next production build separately completed its TypeScript phase.
+
+Quality checks:
+
+```text
+git diff --check
+```
+
+Result: exit 0, no output. Pure LOC counts are 182, 82, 107, 62, 38, and 173 for the six changed
+TypeScript files respectively; every file is below the 200-line healthy ceiling.
+
+Staged audit:
+
+```text
+git diff --cached --check
+git diff --cached --name-status
+git diff --cached --stat
+```
+
+Result: the diff check passed and the staged set contained exactly this report plus the six
+TypeScript implementation/test files listed above (`539 insertions, 39 deletions`). The unrelated
+modified `.superpowers/sdd/task-1-report.md` and untracked `.omo/` tree remained unstaged.
+
+## Self-review
+
+- Single responsibility: the new module owns only onboarding cache identity and transition policy.
+- Boundary purity: the route continues parsing cache payloads with Zod before returning them; the
+  policy receives the parsed payload or `null`.
+- Variant discrimination: the route exhaustively switches over ready, pending, and claim.
+- Privacy: persisted identities contain a version prefix plus SHA-256 only.
+- Atomicity: claims compare the observed version/timestamp; completions compare the exact pending
+  identity and cannot overwrite a newer profile claim.
+- Inputs: the route selects all eight fields included in the fingerprint.
+- Candidate policy: only the newly exposed owner mismatch changed; existing terminal/confidence
+  pairings and representative-time rules remain intact.
+
+## Concerns
+
+- The mandatory repository pre-work command remains blocked by known host issues: system Python
+  3.9 cannot import a PEP 604 annotation, system Python has no pytest, and terminal remote visibility
+  is blocked. No remote-synchronization claim is made.
+- Default Turbopack rejects this worktree's externally pointed `frontend/node_modules` symlink. The
+  webpack production build with the exact CI public placeholders passed completely.
+- The programming skill's standalone no-excuse checker could not resolve its own `typescript`
+  dependency from the external skill cache. Changed-file ESLint, direct pattern audit, full tests,
+  and the production TypeScript build were run instead.
diff --git a/frontend/src/app/api/birth-time-candidate-completion/route.ts b/frontend/src/app/api/birth-time-candidate-completion/route.ts
index 90b4099b..d86196bb 100644
--- a/frontend/src/app/api/birth-time-candidate-completion/route.ts
+++ b/frontend/src/app/api/birth-time-candidate-completion/route.ts
@@ -33,7 +33,7 @@ export async function POST(request: Request) {
       .eq("id", parsed.data.caseId)
       .eq("user_id", user.id)
       .maybeSingle();
-    const time = candidateWorkingTime(stored, parsed.data);
+    const time = candidateWorkingTime(stored, { ...parsed.data, userId: user.id });
     if (caseError || !time) {
       return NextResponse.json(
         { error: "候选结果已变化", message: "请使用当前评估结果继续。" },
diff --git a/frontend/src/app/api/onboarding/route.ts b/frontend/src/app/api/onboarding/route.ts
index ed6b1a11..16941986 100644
--- a/frontend/src/app/api/onboarding/route.ts
+++ b/frontend/src/app/api/onboarding/route.ts
@@ -1,5 +1,10 @@
 import { NextResponse } from "next/server";
 import { z } from "zod";
+import {
+  createOnboardingCacheIdentity,
+  createOnboardingCompletionTransition,
+  decideOnboardingCache,
+} from "@/lib/onboarding-cache-policy";
 import { createAdminSupabaseClient } from "@/lib/supabase/admin";
 import { createServerSupabaseClient } from "@/lib/supabase/server";
 import { getOnboardingAgent } from "@/mastra";
@@ -8,10 +13,6 @@ import { defaultLanguageModel } from "@/mastra/model";
 export const runtime = "nodejs";
 export const maxDuration = 30;
 
-const ONBOARDING_VERSION = "ayanam-onboarding-v3";
-const ONBOARDING_PENDING_VERSION = `${ONBOARDING_VERSION}:pending`;
-const ONBOARDING_CLAIM_TTL_MS = 2 * 60 * 1000;
-
 const onboardingSchema = z.object({
   greeting: z.string().trim().min(8).max(180),
   suggestions: z.tuple([
@@ -95,34 +96,55 @@ export async function POST() {
     );
   }
 
-  if (profile.onboarding_version === ONBOARDING_VERSION) {
-    const cached = onboardingSchema.safeParse(profile.onboarding_payload);
-    if (cached.success) {
-      return NextResponse.json({ ...cached.data, source: "cache" });
-    }
-  }
-
-  const generatedAt = typeof profile.onboarding_generated_at === "string"
+  const identity = createOnboardingCacheIdentity({
+    name: profile.name,
+    birthDate: profile.birth_date,
+    birthTime: profile.birth_time,
+    activeBirthTime: profile.active_birth_time,
+    birthTimeStatus: profile.birth_time_status,
+    countryCode: profile.country_code,
+    provinceCode: profile.province_code,
+    cityCode: profile.city_code,
+  });
+  const cached = onboardingSchema.safeParse(profile.onboarding_payload);
+  const generatedAtMs = typeof profile.onboarding_generated_at === "string"
     ? Date.parse(profile.onboarding_generated_at)
     : 0;
-  const activeClaim = profile.onboarding_version === ONBOARDING_PENDING_VERSION
-    && Number.isFinite(generatedAt)
-    && Date.now() - generatedAt < ONBOARDING_CLAIM_TTL_MS;
-  if (activeClaim) {
-    return NextResponse.json({ ...fallbackPayload, source: "pending" });
+  const cacheDecision = decideOnboardingCache({
+    identity,
+    observedVersion: profile.onboarding_version,
+    generatedAtMs,
+    nowMs: Date.now(),
+    cachedPayload: cached.success ? cached.data : null,
+  });
+
+  switch (cacheDecision.kind) {
+    case "ready":
+      return NextResponse.json({ ...cacheDecision.payload, source: "cache" });
+    case "pending":
+      return NextResponse.json({ ...fallbackPayload, source: "pending" });
+    case "claim":
+      break;
+    default: {
+      const exhaustiveDecision: never = cacheDecision;
+      throw exhaustiveDecision;
+    }
   }
 
   const claimTime = new Date().toISOString();
   let claim = admin
     .from("profiles")
     .update({
-      onboarding_version: ONBOARDING_PENDING_VERSION,
+      onboarding_version: cacheDecision.pendingVersion,
       onboarding_generated_at: claimTime,
     })
     .eq("id", user.id);
-  claim = profile.onboarding_version === null
+  claim = cacheDecision.expectedVersion === null
     ? claim.is("onboarding_version", null)
-    : claim.eq("onboarding_version", profile.onboarding_version);
+    : claim.eq("onboarding_version", cacheDecision.expectedVersion);
+  claim = profile.onboarding_generated_at === null
+    ? claim.is("onboarding_generated_at", null)
+    : claim.eq("onboarding_generated_at", profile.onboarding_generated_at);
   const { data: claimedProfile, error: claimError } = await claim.select("id").maybeSingle();
   if (claimError) {
     return NextResponse.json(
@@ -160,15 +182,16 @@ export async function POST() {
     }
   }
 
+  const completionTransition = createOnboardingCompletionTransition(identity);
   const { error: cacheError } = await admin
     .from("profiles")
     .update({
       onboarding_payload: payload,
-      onboarding_version: ONBOARDING_VERSION,
+      onboarding_version: completionTransition.readyVersion,
       onboarding_generated_at: new Date().toISOString(),
     })
     .eq("id", user.id)
-    .eq("onboarding_version", ONBOARDING_PENDING_VERSION);
+    .eq("onboarding_version", completionTransition.expectedVersion);
 
   if (cacheError) {
     console.warn("[onboarding] unable to cache generated content", cacheError.message);
diff --git a/frontend/src/lib/birth-time-candidate-completion.ts b/frontend/src/lib/birth-time-candidate-completion.ts
index e13b54e5..a018bf2d 100644
--- a/frontend/src/lib/birth-time-candidate-completion.ts
+++ b/frontend/src/lib/birth-time-candidate-completion.ts
@@ -1,4 +1,5 @@
 type CandidateCompletionRequest = {
+  readonly userId: string;
   readonly caseId: string;
   readonly resultId: string;
   readonly time: string;
@@ -29,8 +30,7 @@ export function candidateWorkingTime(
       && assessment?.status === "candidate";
 
   return assessment?.id === request.caseId
-    && typeof assessment?.user_id === "string"
-    && assessment.user_id.length > 0
+    && assessment?.user_id === request.userId
     && terminalStatusMatches
     && assessment.candidate_result_id === request.resultId
     && action?.resultId === request.resultId
diff --git a/frontend/src/lib/onboarding-cache-policy.ts b/frontend/src/lib/onboarding-cache-policy.ts
new file mode 100644
index 00000000..5cc73ac9
--- /dev/null
+++ b/frontend/src/lib/onboarding-cache-policy.ts
@@ -0,0 +1,94 @@
+import { createHash } from "node:crypto";
+
+const ONBOARDING_VERSION = "ayanam-onboarding-v3";
+export const ONBOARDING_CLAIM_TTL_MS = 2 * 60 * 1000;
+
+type OnboardingProfileInput = {
+  readonly name: string | null;
+  readonly birthDate: string | null;
+  readonly birthTime: string | null;
+  readonly activeBirthTime: string | null;
+  readonly birthTimeStatus: string | null;
+  readonly countryCode: string | null;
+  readonly provinceCode: string | null;
+  readonly cityCode: string | null;
+};
+
+export type OnboardingCacheIdentity = {
+  readonly readyVersion: string;
+  readonly pendingVersion: string;
+};
+
+export type OnboardingCompletionTransition = {
+  readonly expectedVersion: string;
+  readonly readyVersion: string;
+};
+
+type OnboardingCacheObservation<Payload> = {
+  readonly identity: OnboardingCacheIdentity;
+  readonly observedVersion: string | null;
+  readonly generatedAtMs: number;
+  readonly nowMs: number;
+  readonly cachedPayload: Payload | null;
+};
+
+type OnboardingCacheDecision<Payload> =
+  | { readonly kind: "ready"; readonly payload: Payload }
+  | { readonly kind: "pending" }
+  | {
+    readonly kind: "claim";
+    readonly expectedVersion: string | null;
+    readonly pendingVersion: string;
+  };
+
+export function createOnboardingCacheIdentity(
+  profile: OnboardingProfileInput,
+): OnboardingCacheIdentity {
+  const fingerprint = createHash("sha256")
+    .update(JSON.stringify([
+      profile.name,
+      profile.birthDate,
+      profile.birthTime,
+      profile.activeBirthTime,
+      profile.birthTimeStatus,
+      profile.countryCode,
+      profile.provinceCode,
+      profile.cityCode,
+    ]))
+    .digest("hex");
+
+  return {
+    readyVersion: `${ONBOARDING_VERSION}:${fingerprint}`,
+    pendingVersion: `${ONBOARDING_VERSION}:pending:${fingerprint}`,
+  };
+}
+
+export function decideOnboardingCache<Payload>(
+  observation: OnboardingCacheObservation<Payload>,
+): OnboardingCacheDecision<Payload> {
+  if (observation.observedVersion === observation.identity.readyVersion
+    && observation.cachedPayload !== null) {
+    return { kind: "ready", payload: observation.cachedPayload };
+  }
+
+  if (observation.observedVersion === observation.identity.pendingVersion
+    && Number.isFinite(observation.generatedAtMs)
+    && observation.nowMs - observation.generatedAtMs < ONBOARDING_CLAIM_TTL_MS) {
+    return { kind: "pending" };
+  }
+
+  return {
+    kind: "claim",
+    expectedVersion: observation.observedVersion,
+    pendingVersion: observation.identity.pendingVersion,
+  };
+}
+
+export function createOnboardingCompletionTransition(
+  identity: OnboardingCacheIdentity,
+): OnboardingCompletionTransition {
+  return {
+    expectedVersion: identity.pendingVersion,
+    readyVersion: identity.readyVersion,
+  };
+}
diff --git a/frontend/tests/birth-time-candidate-completion.test.ts b/frontend/tests/birth-time-candidate-completion.test.ts
index c8a17661..1adaa7c8 100644
--- a/frontend/tests/birth-time-candidate-completion.test.ts
+++ b/frontend/tests/birth-time-candidate-completion.test.ts
@@ -35,25 +35,27 @@ const lowTerminalCase = {
   },
 };
 
+const completionRequest = {
+  userId: terminalCase.user_id,
+  caseId: terminalCase.id,
+  resultId: terminalCase.candidate_result_id,
+  time: "04:53",
+} as const;
+
 test("candidate completion only accepts the persisted terminal representative time", () => {
   assert.equal(candidateWorkingTime(terminalCase, {
-    caseId: terminalCase.id,
-    resultId: terminalCase.candidate_result_id,
-    time: "04:53",
+    ...completionRequest,
   }), "04:53");
 
   assert.equal(candidateWorkingTime(terminalCase, {
-    caseId: terminalCase.id,
-    resultId: terminalCase.candidate_result_id,
+    ...completionRequest,
     time: "04:54",
   }), null);
 });
 
 test("accepts a matching low-confidence result from the rectifying state", () => {
   assert.equal(candidateWorkingTime(lowTerminalCase, {
-    caseId: terminalCase.id,
-    resultId: terminalCase.candidate_result_id,
-    time: "04:53",
+    ...completionRequest,
   }), "04:53");
 });
 
@@ -68,9 +70,7 @@ test("does not accept a medium terminal action from the rectifying state", () =>
       },
     },
   }, {
-    caseId: terminalCase.id,
-    resultId: terminalCase.candidate_result_id,
-    time: "04:53",
+    ...completionRequest,
   }), null);
 });
 
@@ -79,8 +79,105 @@ test("non-terminal cases cannot be adopted for consultation", () => {
     ...terminalCase,
     turn_state: { nextAction: { kind: "ask_dynamic_choice" } },
   }, {
-    caseId: terminalCase.id,
-    resultId: terminalCase.candidate_result_id,
-    time: "04:53",
+    ...completionRequest,
   }), null);
 });
+
+const rejectedCompletions = [
+  {
+    name: "case owned by another user",
+    stored: { ...terminalCase, user_id: "f6cf99a5-9af7-4980-93ea-0298ee1dc95e" },
+    request: completionRequest,
+  },
+  {
+    name: "request from another user",
+    stored: terminalCase,
+    request: { ...completionRequest, userId: "f6cf99a5-9af7-4980-93ea-0298ee1dc95e" },
+  },
+  {
+    name: "wrong case ID",
+    stored: terminalCase,
+    request: { ...completionRequest, caseId: "c84052ca-bcea-40a8-a32a-56980bbf7b22" },
+  },
+  {
+    name: "wrong persisted result ID",
+    stored: { ...terminalCase, candidate_result_id: "a3e41512-9fa0-4866-a187-e3b3aa07aee0" },
+    request: completionRequest,
+  },
+  {
+    name: "wrong action result ID",
+    stored: {
+      ...terminalCase,
+      turn_state: {
+        nextAction: {
+          ...terminalCase.turn_state.nextAction,
+          resultId: "a3e41512-9fa0-4866-a187-e3b3aa07aee0",
+        },
+      },
+    },
+    request: completionRequest,
+  },
+  {
+    name: "wrong requested result ID",
+    stored: terminalCase,
+    request: { ...completionRequest, resultId: "a3e41512-9fa0-4866-a187-e3b3aa07aee0" },
+  },
+  {
+    name: "missing winning segment",
+    stored: { ...terminalCase, candidate_result: { confidence: "medium" } },
+    request: completionRequest,
+  },
+  {
+    name: "missing representative time",
+    stored: {
+      ...terminalCase,
+      candidate_result: { confidence: "medium", winningSegment: {} },
+    },
+    request: completionRequest,
+  },
+  {
+    name: "low-result action paired with candidate status",
+    stored: {
+      ...terminalCase,
+      turn_state: {
+        nextAction: {
+          kind: "present_low_result",
+          resultId: terminalCase.candidate_result_id,
+        },
+      },
+    },
+    request: completionRequest,
+  },
+  {
+    name: "medium-result action paired with rectifying status",
+    stored: {
+      ...lowTerminalCase,
+      turn_state: {
+        nextAction: {
+          kind: "present_medium_result",
+          resultId: terminalCase.candidate_result_id,
+        },
+      },
+    },
+    request: completionRequest,
+  },
+  {
+    name: "candidate-saved action paired with rectifying status",
+    stored: {
+      ...lowTerminalCase,
+      turn_state: {
+        nextAction: {
+          kind: "candidate_saved",
+          resultId: terminalCase.candidate_result_id,
+        },
+      },
+    },
+    request: completionRequest,
+  },
+] as const;
+
+for (const scenario of rejectedCompletions) {
+  test(`rejects candidate completion with ${scenario.name}`, () => {
+    assert.equal(candidateWorkingTime(scenario.stored, scenario.request), null);
+  });
+}
diff --git a/frontend/tests/onboarding-cache-policy.test.ts b/frontend/tests/onboarding-cache-policy.test.ts
new file mode 100644
index 00000000..d5ed6914
--- /dev/null
+++ b/frontend/tests/onboarding-cache-policy.test.ts
@@ -0,0 +1,134 @@
+import assert from "node:assert/strict";
+import test from "node:test";
+import {
+  createOnboardingCacheIdentity,
+  createOnboardingCompletionTransition,
+  decideOnboardingCache,
+} from "../src/lib/onboarding-cache-policy.ts";
+
+const profileA = {
+  name: "林遥",
+  birthDate: "1990-06-15",
+  birthTime: "12:30",
+  activeBirthTime: "12:30",
+  birthTimeStatus: "confirmed",
+  countryCode: "CN",
+  provinceCode: "110000",
+  cityCode: "110100",
+} as const;
+
+test("changed profile cannot reuse a ready cache from the previous profile", () => {
+  // Given: profile A has a valid ready cache.
+  const identityA = createOnboardingCacheIdentity(profileA);
+  const identityB = createOnboardingCacheIdentity({ ...profileA, name: "周宁" });
+
+  // When: profile B observes A's ready version.
+  const decision = decideOnboardingCache({
+    identity: identityB,
+    observedVersion: identityA.readyVersion,
+    generatedAtMs: Date.parse("2026-07-19T10:00:00.000Z"),
+    nowMs: Date.parse("2026-07-19T10:00:01.000Z"),
+    cachedPayload: {},
+  });
+
+  // Then: B must claim its own pending identity from the exact observed version.
+  assert.deepEqual(decision, {
+    kind: "claim",
+    expectedVersion: identityA.readyVersion,
+    pendingVersion: identityB.pendingVersion,
+  });
+  assert.notEqual(identityA.readyVersion, identityB.readyVersion);
+  assert.doesNotMatch(identityB.readyVersion, /周宁|1990|12:30|110000/);
+});
+
+test("changed profile cannot wait on the previous profile's active pending claim", () => {
+  // Given: profile A has a fresh pending claim.
+  const identityA = createOnboardingCacheIdentity(profileA);
+  const identityB = createOnboardingCacheIdentity({ ...profileA, activeBirthTime: "12:45" });
+
+  // When: profile B observes A's pending version within the claim TTL.
+  const decision = decideOnboardingCache({
+    identity: identityB,
+    observedVersion: identityA.pendingVersion,
+    generatedAtMs: Date.parse("2026-07-19T10:00:00.000Z"),
+    nowMs: Date.parse("2026-07-19T10:00:01.000Z"),
+    cachedPayload: null,
+  });
+
+  // Then: B claims immediately instead of returning A's pending response.
+  assert.deepEqual(decision, {
+    kind: "claim",
+    expectedVersion: identityA.pendingVersion,
+    pendingVersion: identityB.pendingVersion,
+  });
+});
+
+test("stale profile completion loses ownership after the current profile claims", () => {
+  // Given: B has replaced A's pending identity in the row.
+  const identityA = createOnboardingCacheIdentity(profileA);
+  const identityB = createOnboardingCacheIdentity({ ...profileA, cityCode: "310100" });
+  const rowVersionAfterBClaims = identityB.pendingVersion;
+
+  // When: each completion prepares an exact compare-and-set transition.
+  const completionA = createOnboardingCompletionTransition(identityA);
+  const completionB = createOnboardingCompletionTransition(identityB);
+
+  // Then: A cannot match the row, while B can commit its own ready identity.
+  assert.notEqual(rowVersionAfterBClaims, completionA.expectedVersion);
+  assert.equal(rowVersionAfterBClaims, completionB.expectedVersion);
+  assert.equal(completionB.readyVersion, identityB.readyVersion);
+});
+
+test("current profile accepts only valid ready content and an active current pending claim", () => {
+  // Given: one current profile identity and a valid cached payload.
+  const identity = createOnboardingCacheIdentity(profileA);
+  const payload = { greeting: "current" };
+  const nowMs = Date.parse("2026-07-19T10:01:00.000Z");
+
+  // When/Then: exact ready and fresh pending identities retain their existing behavior.
+  assert.deepEqual(decideOnboardingCache({
+    identity,
+    observedVersion: identity.readyVersion,
+    generatedAtMs: nowMs - 60_000,
+    nowMs,
+    cachedPayload: payload,
+  }), { kind: "ready", payload });
+  assert.deepEqual(decideOnboardingCache({
+    identity,
+    observedVersion: identity.pendingVersion,
+    generatedAtMs: nowMs - 60_000,
+    nowMs,
+    cachedPayload: null,
+  }), { kind: "pending" });
+});
+
+test("invalid ready content and expired pending claims are reclaimed", () => {
+  // Given: the current profile sees unusable ready content or an expired pending claim.
+  const identity = createOnboardingCacheIdentity(profileA);
+  const nowMs = Date.parse("2026-07-19T10:03:00.000Z");
+  const observations = [
+    {
+      identity,
+      observedVersion: identity.readyVersion,
+      generatedAtMs: nowMs - 1_000,
+      nowMs,
+      cachedPayload: null,
+    },
+    {
+      identity,
+      observedVersion: identity.pendingVersion,
+      generatedAtMs: nowMs - 180_000,
+      nowMs,
+      cachedPayload: null,
+    },
+  ] as const;
+
+  // When/Then: each stale state becomes a compare-and-set claim for the current identity.
+  for (const observation of observations) {
+    assert.deepEqual(decideOnboardingCache(observation), {
+      kind: "claim",
+      expectedVersion: observation.observedVersion,
+      pendingVersion: identity.pendingVersion,
+    });
+  }
+});