diff --git a/docs/contributing/testing.md b/docs/contributing/testing.md
index 741528ed9..100e9a043 100644
--- a/docs/contributing/testing.md
+++ b/docs/contributing/testing.md
@@ -121,7 +121,9 @@ Each Vitest worker clones it on its first file (`CREATE DATABASE … TEMPLATE`,
 see `tests/integration/worker-database.ts`), so files run in parallel without
 seeing each other's rows, advisory locks or queue schema. The worker count
 follows the host (half the cores, at most eight) unless
-`HEALTHLOG_INTEGRATION_WORKERS` pins it; CI uses three.
+`HEALTHLOG_INTEGRATION_WORKERS` pins it; CI uses three. To reproduce a CI runner's
+contention on a larger machine, cap the database container with
+`HEALTHLOG_INTEGRATION_PG_CPUS=2`.
 
 `truncateAllTables` empties every table the migrations created and puts back
 the rows they seed (the mood-tag and symptom catalogues), so a test starts
diff --git a/tests/integration/dashboard-summary-reads.test.ts b/tests/integration/dashboard-summary-reads.test.ts
index 979c6746f..5df8ac0bd 100644
--- a/tests/integration/dashboard-summary-reads.test.ts
+++ b/tests/integration/dashboard-summary-reads.test.ts
@@ -335,5 +335,12 @@ describe("dashboard all-time counts — parity with the live count", () => {
     expect(legacy.get("PULSE")).toBeGreaterThan(500_000);
     expect(legacy.get("WEIGHT")).toBe(5);
     expect(legacy.get("BLOOD_GLUCOSE")).toBe(2);
-  });
+    // Over half a million rows written and folded into DAY buckets: about
+    // 35 s on a CI runner when the file ran alone. With three files sharing
+    // the runner's Postgres it took 1.7 times as long (measured with the
+    // database capped at two CPUs, HEALTHLOG_INTEGRATION_PG_CPUS=2: 14.6 s
+    // alone, 25.3 s beside the sharing matrix and the restore memory test),
+    // past the suite's 60 s default. The work is the point of the case, so
+    // the budget is sized to it: twice the contended estimate.
+  }, 150_000);
 });
diff --git a/tests/integration/global-setup.ts b/tests/integration/global-setup.ts
index 31fdc912b..da31f7124 100644
--- a/tests/integration/global-setup.ts
+++ b/tests/integration/global-setup.ts
@@ -44,7 +44,7 @@ const __filename = fileURLToPath(import.meta.url);
 const __dirname = dirname(__filename);
 const PROJECT_ROOT = resolve(__dirname, "..", "..");
 
-let container: StartedPostgreSqlContainer | null = null;
+let started: StartedPostgreSqlContainer | null = null;
 
 declare module "vitest" {
   export interface ProvidedContext {
@@ -56,7 +56,7 @@ declare module "vitest" {
 export default async function setup(
   project: TestProject,
 ): Promise<() => Promise<void>> {
-  container = await new PostgreSqlContainer("postgres:16-alpine")
+  let container = new PostgreSqlContainer("postgres:16-alpine")
     .withDatabase(TEMPLATE_DATABASE)
     .withUsername("healthlog")
     .withPassword("healthlog")
@@ -74,10 +74,18 @@ export default async function setup(
       "full_page_writes=off",
       "-c",
       "max_connections=400",
-    ])
-    .start();
+    ]);
+  // A CPU quota for the database container, to reproduce a CI runner's
+  // contention on a larger machine: HEALTHLOG_INTEGRATION_PG_CPUS=2.
+  const cpus = Number.parseFloat(
+    process.env.HEALTHLOG_INTEGRATION_PG_CPUS ?? "",
+  );
+  if (Number.isFinite(cpus) && cpus > 0) {
+    container = container.withResourcesQuota({ cpu: cpus });
+  }
+  started = await container.start();
 
-  const url = container.getConnectionUri() + "?schema=public&pgbouncer=false";
+  const url = started.getConnectionUri() + "?schema=public&pgbouncer=false";
   process.env.DATABASE_URL = url;
 
   // The explicit child environment keeps Prisma CLI on the same container.
@@ -91,9 +99,9 @@ export default async function setup(
   project.provide("integrationDatabasePlan", await readTemplate(url));
 
   return async () => {
-    if (container) {
-      await container.stop({ remove: true });
-      container = null;
+    if (started) {
+      await started.stop({ remove: true });
+      started = null;
     }
   };
 }
diff --git a/tests/integration/migrate-deploy-lock-retry.test.ts b/tests/integration/migrate-deploy-lock-retry.test.ts
index b9678feaf..d4b0c6137 100644
--- a/tests/integration/migrate-deploy-lock-retry.test.ts
+++ b/tests/integration/migrate-deploy-lock-retry.test.ts
@@ -145,6 +145,47 @@ async function holdLock(): Promise<Client> {
   return holder;
 }
 
+/** Sessions of this database queued behind a lock, other than the holder. */
+async function lockWaiters(db: Client, holderPid: number): Promise<number> {
+  const { rows } = await db.query<{ n: string }>(
+    `SELECT count(*) AS n FROM pg_stat_activity
+      WHERE datname = current_database()
+        AND wait_event_type = 'Lock'
+        AND pid <> $1`,
+    [holderPid],
+  );
+  return Number(rows[0]?.n ?? 0);
+}
+
+/**
+ * Let go of the held lock once a migration attempt has queued behind it and
+ * given up. Resolves false when no attempt queued within the budget, so the
+ * test reports that instead of passing on a run that never met the lock.
+ */
+async function releaseAfterFirstTimeout(holder: Client): Promise<boolean> {
+  const { rows } = await holder.query<{ pid: number }>(
+    "SELECT pg_backend_pid() AS pid",
+  );
+  const holderPid = rows[0].pid;
+  const watcher = await connect();
+  const until = async (predicate: (n: number) => boolean) => {
+    const deadline = Date.now() + 60_000;
+    while (Date.now() < deadline) {
+      if (predicate(await lockWaiters(watcher, holderPid))) return true;
+      await new Promise((resolve) => setTimeout(resolve, 25));
+    }
+    return false;
+  };
+  try {
+    const queued = await until((n) => n > 0);
+    if (queued) await until((n) => n === 0);
+    await holder.query("ROLLBACK");
+    return queued;
+  } finally {
+    await watcher.end();
+  }
+}
+
 async function state(db: Client) {
   const rows = await db.query(
     `SELECT migration_name, finished_at IS NOT NULL AS finished,
@@ -181,15 +222,23 @@ describe("migration 0412 under a held lock", () => {
     add0412(dir, { marked: true });
     const holder = await holdLock();
     // The first attempt meets the lock; the holder lets go during the backoff.
-    const release = setTimeout(() => {
-      void holder.query("ROLLBACK");
-    }, 2_500);
+    // The release follows the migration rather than a clock: it waits until
+    // the first attempt is seen queued behind the lock and then gone again
+    // (its one-second timeout fired), and lets go before the retry. A fixed
+    // delay raced the CLI's own start-up, which on a loaded runner outlasted
+    // the delay, so the first attempt found the lock already free.
+    const released = releaseAfterFirstTimeout(holder);
     const startedAt = Date.now();
     const result = await migrateDeploy(dir);
-    clearTimeout(release);
+    const releasedInTime = await released;
     await holder.query("ROLLBACK").catch(() => {});
     await holder.end();
 
+    expect(
+      releasedInTime,
+      "the first attempt never queued behind the held lock",
+    ).toBe(true);
+
     expect(result.code, result.stderr).toBe(0);
     expect(result.stderr).toContain("Database error code: 55P03");
     expect(result.stdout).toContain(