diff --git a/scripts/__tests__/run-vitest-stable-shard.test.mjs b/scripts/__tests__/run-vitest-stable-shard.test.mjs
index 889c5fb066..7d0da8ea99 100644
--- a/scripts/__tests__/run-vitest-stable-shard.test.mjs
+++ b/scripts/__tests__/run-vitest-stable-shard.test.mjs
@@ -4,8 +4,15 @@ import path from "node:path";
 import { fileURLToPath } from "node:url";
 import test from "node:test";
 
+import {
+  defaultSuiteWeight,
+  loadShardDurations,
+  partitionGeneralServerSuites,
+} from "../general-server-shard.mjs";
+
 const repoRoot = path.resolve(path.dirname(fileURLToPath(import.meta.url)), "..", "..");
 const script = path.join(repoRoot, "scripts", "run-vitest-stable.mjs");
+const durationsManifest = path.join(repoRoot, "scripts", "general-server-shard-durations.json");
 
 function dryRun(args) {
   const result = spawnSync(process.execPath, [script, ...args, "--dry-run"], {
@@ -61,3 +68,80 @@ test("shard flags are rejected for the parallel workspace groups", () => {
   const result = dryRun(["--mode", "general", "--group", "general-workspaces-a", "--shard-index", "0", "--shard-count", "3"]);
   assert.notEqual(result.status, 0, "workspace groups must not accept shard flags");
 });
+
+test("duration-aware partition balances skewed weights better than round-robin", () => {
+  // Round-robin puts all three heavy suites on shard 0 (indexes 0, 3, 6).
+  const files = ["a", "b", "c", "d", "e", "f", "g", "h", "i"];
+  const durations = { a: 30000, d: 30000, g: 30000, b: 100, c: 100, e: 100, f: 100, h: 100, i: 100 };
+
+  const shards = partitionGeneralServerSuites(files, 3, durations);
+  const totals = shards.map((shard) => shard.totalWeight);
+  const maxTotal = Math.max(...totals);
+  const minTotal = Math.min(...totals);
+  assert.ok(
+    maxTotal - minTotal <= 200,
+    `expected near-even shard weights, got ${totals.join(", ")}`,
+  );
+  assert.equal(
+    shards.flatMap((shard) => shard.files).sort().join(","),
+    files.join(","),
+    "partition must cover every file exactly once",
+  );
+});
+
+test("the partition is deterministic for identical inputs", () => {
+  const files = Array.from({ length: 50 }, (_, index) => `suite-${index}.test.ts`);
+  const durations = Object.fromEntries(files.map((file, index) => [file, (index * 37) % 5000]));
+
+  const first = partitionGeneralServerSuites(files, 3, durations);
+  const second = partitionGeneralServerSuites(files, 3, durations);
+  assert.deepEqual(first, second, "same inputs must always produce the same partition");
+});
+
+test("suites missing from the manifest get the median weight", () => {
+  assert.equal(defaultSuiteWeight({ a: 100, b: 300, c: 900 }), 300);
+  assert.equal(defaultSuiteWeight({ a: 100, b: 300, c: 500, d: 900 }), 400);
+  assert.equal(defaultSuiteWeight({}), 1000, "empty manifest falls back to a fixed weight");
+});
+
+test("a missing or malformed manifest degrades to uniform weights", () => {
+  assert.deepEqual(loadShardDurations(path.join(repoRoot, "scripts", "no-such-manifest.json")), {});
+
+  const files = ["a", "b", "c", "d"];
+  const shards = partitionGeneralServerSuites(files, 2, {});
+  assert.equal(shards[0].files.length + shards[1].files.length, files.length);
+  assert.equal(Math.abs(shards[0].files.length - shards[1].files.length), 0);
+});
+
+test("the checked-in manifest loads and covers most of the current suite set", () => {
+  const durations = loadShardDurations(durationsManifest);
+  assert.ok(Object.keys(durations).length > 0, "manifest must parse to a non-empty duration map");
+
+  const shard = dryRunJson(["--mode", "general", "--group", "general-server", "--shard-index", "0", "--shard-count", "1"]);
+  const currentFiles = shard.selectedGeneralServerSuites;
+  const known = currentFiles.filter((file) => durations[file] !== undefined).length;
+  assert.ok(
+    known / currentFiles.length >= 0.5,
+    `manifest is stale: only ${known} of ${currentFiles.length} suites have recorded durations — regenerate it from a recent PR run (see the manifest's $comment)`,
+  );
+});
+
+test("the real shard partition is duration-balanced", () => {
+  const durations = loadShardDurations(durationsManifest);
+  const fallback = defaultSuiteWeight(durations);
+  const shards = Array.from({ length: SHARD_COUNT }, (_, index) =>
+    dryRunJson(["--mode", "general", "--group", "general-server", "--shard-index", String(index), "--shard-count", String(SHARD_COUNT)]),
+  );
+
+  const totals = shards.map((shard) =>
+    shard.selectedGeneralServerSuites.reduce((sum, file) => sum + (durations[file] ?? fallback), 0),
+  );
+  const maxTotal = Math.max(...totals);
+  const minTotal = Math.min(...totals);
+  // LPT keeps the spread within the heaviest single suite; use that as the bound.
+  const heaviest = Math.max(...Object.values(durations));
+  assert.ok(
+    maxTotal - minTotal <= heaviest,
+    `shard weight spread ${maxTotal - minTotal}ms exceeds heaviest suite ${heaviest}ms: ${totals.join(", ")}`,
+  );
+});
diff --git a/scripts/general-server-shard-durations.json b/scripts/general-server-shard-durations.json
new file mode 100644
index 0000000000..8b73e9318c
--- /dev/null
+++ b/scripts/general-server-shard-durations.json
@@ -0,0 +1,246 @@
+{
+  "$comment": "Per-suite wall-clock durations (ms) for the general-server vitest lane, used by scripts/general-server-shard.mjs to balance suites across the PR shard matrix. Sampled from a real PR run of .github/workflows/pr.yml (actions run 29262068391, 2026-07-13). Suites missing here get the median weight, so the manifest only needs occasional refreshes: pull the 'Run grouped general test suites' logs from a recent PR run and record each suite's vitest-reported duration.",
+  "unit": "ms",
+  "durations": {
+    "server/src/__tests__/access-service.test.ts": 2303,
+    "server/src/__tests__/access-validators.test.ts": 7,
+    "server/src/__tests__/activity-service.test.ts": 2390,
+    "server/src/__tests__/adapter-models.test.ts": 61,
+    "server/src/__tests__/adapter-registry.test.ts": 17,
+    "server/src/__tests__/adapter-session-codecs.test.ts": 10,
+    "server/src/__tests__/agent-auth-jwt.test.ts": 20,
+    "server/src/__tests__/agent-auth-middleware.test.ts": 66,
+    "server/src/__tests__/agent-instructions-service.test.ts": 58,
+    "server/src/__tests__/agent-invokability.test.ts": 5,
+    "server/src/__tests__/agent-permissions-service.test.ts": 6,
+    "server/src/__tests__/agent-shortname-collision.test.ts": 5,
+    "server/src/__tests__/agent-skill-contract.test.ts": 6,
+    "server/src/__tests__/agents-pending-approval-config.test.ts": 2182,
+    "server/src/__tests__/agents-service-clear-error.test.ts": 2258,
+    "server/src/__tests__/agents-service-secret-bindings.test.ts": 2367,
+    "server/src/__tests__/api-compression.test.ts": 77,
+    "server/src/__tests__/app-hmr-port.test.ts": 4,
+    "server/src/__tests__/app-private-hostname-gate.test.ts": 4,
+    "server/src/__tests__/app-vite-dev-routing.test.ts": 4,
+    "server/src/__tests__/approvals-service.test.ts": 12,
+    "server/src/__tests__/attachment-types.test.ts": 9,
+    "server/src/__tests__/attention-service.test.ts": 2626,
+    "server/src/__tests__/authorization-service.test.ts": 2824,
+    "server/src/__tests__/aws-secrets-manager-provider.test.ts": 39,
+    "server/src/__tests__/better-auth.test.ts": 9,
+    "server/src/__tests__/board-claim.test.ts": 2121,
+    "server/src/__tests__/board-mutation-guard.test.ts": 50,
+    "server/src/__tests__/body-limits.test.ts": 3,
+    "server/src/__tests__/budgets-service.test.ts": 2211,
+    "server/src/__tests__/built-in-agents.test.ts": 6157,
+    "server/src/__tests__/change-consent-gate.test.ts": 2256,
+    "server/src/__tests__/claude-local-adapter-environment.test.ts": 372,
+    "server/src/__tests__/claude-local-adapter.test.ts": 8,
+    "server/src/__tests__/claude-local-execute.test.ts": 2771,
+    "server/src/__tests__/claude-local-skill-sync.test.ts": 21,
+    "server/src/__tests__/cleanup-removal-service.test.ts": 2248,
+    "server/src/__tests__/cloud-upstreams.test.ts": 2576,
+    "server/src/__tests__/codex-auth-reconciliation.test.ts": 46,
+    "server/src/__tests__/codex-local-adapter.test.ts": 9,
+    "server/src/__tests__/codex-local-execute.test.ts": 974,
+    "server/src/__tests__/codex-local-skill-injection.test.ts": 29,
+    "server/src/__tests__/codex-local-skill-sync.test.ts": 18,
+    "server/src/__tests__/companies-service.test.ts": 3104,
+    "server/src/__tests__/company-artifacts-service.test.ts": 2531,
+    "server/src/__tests__/company-search-service.test.ts": 3127,
+    "server/src/__tests__/company-skill-test-runs-service.test.ts": 3331,
+    "server/src/__tests__/company-skills-catalog-service.test.ts": 3584,
+    "server/src/__tests__/company-skills-detail.test.ts": 2258,
+    "server/src/__tests__/company-skills-service.test.ts": 5470,
+    "server/src/__tests__/company-skills.test.ts": 33,
+    "server/src/__tests__/cursor-local-adapter-environment.test.ts": 232,
+    "server/src/__tests__/cursor-local-adapter.test.ts": 11,
+    "server/src/__tests__/cursor-local-execute.test.ts": 1028,
+    "server/src/__tests__/cursor-local-skill-injection.test.ts": 15,
+    "server/src/__tests__/cursor-local-skill-sync.test.ts": 22,
+    "server/src/__tests__/dashboard-service.test.ts": 2222,
+    "server/src/__tests__/dev-runner-output.test.ts": 25,
+    "server/src/__tests__/dev-runner-paths.test.ts": 4,
+    "server/src/__tests__/dev-runner-snapshot.test.ts": 8,
+    "server/src/__tests__/dev-runner-worktree.test.ts": 7,
+    "server/src/__tests__/dev-server-status.test.ts": 7,
+    "server/src/__tests__/dev-watch-ignore.test.ts": 7,
+    "server/src/__tests__/docker-entrypoint.test.ts": 39,
+    "server/src/__tests__/document-annotations-service.test.ts": 2528,
+    "server/src/__tests__/documents-service.test.ts": 2253,
+    "server/src/__tests__/documents.test.ts": 4,
+    "server/src/__tests__/effective-run-config-fingerprints.test.ts": 10,
+    "server/src/__tests__/environment-config.test.ts": 11,
+    "server/src/__tests__/environment-custom-image-terminal-ws.test.ts": 2566,
+    "server/src/__tests__/environment-custom-images-service.test.ts": 3889,
+    "server/src/__tests__/environment-execution-target.test.ts": 7,
+    "server/src/__tests__/environment-live-ssh.test.ts": 717,
+    "server/src/__tests__/environment-probe.test.ts": 12,
+    "server/src/__tests__/environment-run-orchestrator.test.ts": 13,
+    "server/src/__tests__/environment-runtime-driver-contract.test.ts": 2723,
+    "server/src/__tests__/environment-runtime.test.ts": 3287,
+    "server/src/__tests__/environment-service.test.ts": 2266,
+    "server/src/__tests__/environment-test-harness.test.ts": 14,
+    "server/src/__tests__/error-handler.test.ts": 12,
+    "server/src/__tests__/execution-lock-orphan-cleanup.test.ts": 2333,
+    "server/src/__tests__/execution-workspace-policy.test.ts": 9,
+    "server/src/__tests__/execution-workspaces-service.test.ts": 6035,
+    "server/src/__tests__/external-objects-service.test.ts": 2282,
+    "server/src/__tests__/feedback-flush-controller.test.ts": 4,
+    "server/src/__tests__/feedback-service.test.ts": 2520,
+    "server/src/__tests__/feedback-share-client.test.ts": 9,
+    "server/src/__tests__/file-resources.test.ts": 4757,
+    "server/src/__tests__/first-admin-claim.test.ts": 2117,
+    "server/src/__tests__/forbidden-tokens.test.ts": 6,
+    "server/src/__tests__/gemini-local-adapter-environment.test.ts": 80,
+    "server/src/__tests__/gemini-local-adapter.test.ts": 9,
+    "server/src/__tests__/gemini-local-execute.test.ts": 220,
+    "server/src/__tests__/gemini-local-skill-sync.test.ts": 18,
+    "server/src/__tests__/grok-local-skill-sync.test.ts": 15,
+    "server/src/__tests__/heartbeat-accepted-plan-workspace-refresh.test.ts": 5034,
+    "server/src/__tests__/heartbeat-active-run-output-watchdog.test.ts": 49231,
+    "server/src/__tests__/heartbeat-archived-company-guard.test.ts": 2303,
+    "server/src/__tests__/heartbeat-auto-checkout.test.ts": 5,
+    "server/src/__tests__/heartbeat-comment-wake-batching.test.ts": 5030,
+    "server/src/__tests__/heartbeat-context-summary.test.ts": 8,
+    "server/src/__tests__/heartbeat-issue-rewake-throttle.test.ts": 3198,
+    "server/src/__tests__/heartbeat-list.test.ts": 2240,
+    "server/src/__tests__/heartbeat-local-environment.test.ts": 2504,
+    "server/src/__tests__/heartbeat-lock-release-on-reassignment.test.ts": 2129,
+    "server/src/__tests__/heartbeat-model-profile.test.ts": 6,
+    "server/src/__tests__/heartbeat-plugin-environment.test.ts": 2310,
+    "server/src/__tests__/heartbeat-project-env.test.ts": 24,
+    "server/src/__tests__/heartbeat-responsible-user-invariant.test.ts": 6285,
+    "server/src/__tests__/heartbeat-retry-scheduling.test.ts": 3373,
+    "server/src/__tests__/heartbeat-run-log.test.ts": 5,
+    "server/src/__tests__/heartbeat-run-summary.test.ts": 6,
+    "server/src/__tests__/heartbeat-runtime-skills.test.ts": 2681,
+    "server/src/__tests__/heartbeat-runtime-state.test.ts": 2322,
+    "server/src/__tests__/heartbeat-scheduling-suppression.test.ts": 5,
+    "server/src/__tests__/heartbeat-stale-queue-invalidation.test.ts": 11573,
+    "server/src/__tests__/heartbeat-start-lock.test.ts": 8,
+    "server/src/__tests__/heartbeat-timer-wake-session-reset-pf4.test.ts": 6,
+    "server/src/__tests__/heartbeat-workspace-branch-containment.test.ts": 6144,
+    "server/src/__tests__/heartbeat-workspace-finalize-branch.test.ts": 3599,
+    "server/src/__tests__/heartbeat-workspace-session.test.ts": 185,
+    "server/src/__tests__/heartbeat-worktree-suppression.test.ts": 2665,
+    "server/src/__tests__/heartbeat-zombie-guard.test.ts": 5,
+    "server/src/__tests__/hire-hook.test.ts": 14,
+    "server/src/__tests__/http-log-policy.test.ts": 5,
+    "server/src/__tests__/inbox-dismissals.test.ts": 2110,
+    "server/src/__tests__/instance-settings-service.test.ts": 15,
+    "server/src/__tests__/instrumentation.test.ts": 27,
+    "server/src/__tests__/invite-join-grants.test.ts": 6,
+    "server/src/__tests__/issue-blocker-attention.test.ts": 3329,
+    "server/src/__tests__/issue-comment-redaction.test.ts": 2383,
+    "server/src/__tests__/issue-continuation-summary.test.ts": 6,
+    "server/src/__tests__/issue-execution-policy.test.ts": 35,
+    "server/src/__tests__/issue-goal-fallback.test.ts": 5,
+    "server/src/__tests__/issue-liveness.test.ts": 14,
+    "server/src/__tests__/issue-monitor-scheduler.test.ts": 6810,
+    "server/src/__tests__/issue-recovery-actions.test.ts": 3556,
+    "server/src/__tests__/issue-references-service.test.ts": 2184,
+    "server/src/__tests__/issue-rewake-throttle.test.ts": 7,
+    "server/src/__tests__/issue-thread-interactions-service.test.ts": 3053,
+    "server/src/__tests__/issue-thread-interactions-telemetry.test.ts": 2209,
+    "server/src/__tests__/issue-tree-control-service-unit.test.ts": 6,
+    "server/src/__tests__/issue-tree-control-service.test.ts": 2498,
+    "server/src/__tests__/issues-list-query-parsing.test.ts": 42,
+    "server/src/__tests__/issues-user-context.test.ts": 5,
+    "server/src/__tests__/join-request-dedupe.test.ts": 4,
+    "server/src/__tests__/json-schema-secret-refs.test.ts": 4,
+    "server/src/__tests__/live-events-ws.test.ts": 21,
+    "server/src/__tests__/log-redaction.test.ts": 6,
+    "server/src/__tests__/logger-tz.test.ts": 24,
+    "server/src/__tests__/monthly-spend-service.test.ts": 29,
+    "server/src/__tests__/openclaw-gateway-adapter.test.ts": 52,
+    "server/src/__tests__/opencode-local-adapter.test.ts": 8,
+    "server/src/__tests__/opencode-local-skill-sync.test.ts": 17,
+    "server/src/__tests__/paperclip-env.test.ts": 5,
+    "server/src/__tests__/paperclip-skill-utils.test.ts": 18,
+    "server/src/__tests__/parse-status-filter.test.ts": 6,
+    "server/src/__tests__/pi-local-adapter-environment.test.ts": 128,
+    "server/src/__tests__/pi-local-execute.test.ts": 228,
+    "server/src/__tests__/pi-local-skill-sync.test.ts": 17,
+    "server/src/__tests__/pipelines-service.test.ts": 4478,
+    "server/src/__tests__/plugin-access-authorization-host-services.test.ts": 2259,
+    "server/src/__tests__/plugin-database.test.ts": 2422,
+    "server/src/__tests__/plugin-dev-watcher.test.ts": 67,
+    "server/src/__tests__/plugin-environment-driver-seam.test.ts": 55,
+    "server/src/__tests__/plugin-execution-workspace-bridge.test.ts": 7,
+    "server/src/__tests__/plugin-install-autobuild.test.ts": 4336,
+    "server/src/__tests__/plugin-lifecycle-restart.test.ts": 7,
+    "server/src/__tests__/plugin-local-folders.test.ts": 63,
+    "server/src/__tests__/plugin-managed-agents.test.ts": 2407,
+    "server/src/__tests__/plugin-managed-routines.test.ts": 2371,
+    "server/src/__tests__/plugin-managed-skills.test.ts": 2600,
+    "server/src/__tests__/plugin-orchestration-apis.test.ts": 2531,
+    "server/src/__tests__/plugin-sdk-orchestration-contract.test.ts": 13,
+    "server/src/__tests__/plugin-sdk-testing.test.ts": 10,
+    "server/src/__tests__/plugin-secrets-handler.test.ts": 5,
+    "server/src/__tests__/plugin-telemetry-bridge.test.ts": 36,
+    "server/src/__tests__/plugin-tenant-isolation.test.ts": 2264,
+    "server/src/__tests__/plugin-tool-dispatcher-pluginDbId.test.ts": 12,
+    "server/src/__tests__/plugin-worker-manager.test.ts": 355,
+    "server/src/__tests__/private-hostname-guard.test.ts": 39,
+    "server/src/__tests__/productivity-review-service.test.ts": 5180,
+    "server/src/__tests__/project-icon-persistence.test.ts": 2091,
+    "server/src/__tests__/project-list-metrics.test.ts": 5,
+    "server/src/__tests__/project-shortname-resolution.test.ts": 5,
+    "server/src/__tests__/qa-routine-secrets-e2e.test.ts": 2364,
+    "server/src/__tests__/quota-windows-service.test.ts": 7,
+    "server/src/__tests__/quota-windows.test.ts": 59,
+    "server/src/__tests__/recovery-classifiers.test.ts": 9,
+    "server/src/__tests__/recovery-stale-issue-lock-sweep.test.ts": 2250,
+    "server/src/__tests__/redact-sensitive.test.ts": 7,
+    "server/src/__tests__/routine-run-telemetry.test.ts": 2157,
+    "server/src/__tests__/routines-service.test.ts": 5411,
+    "server/src/__tests__/run-continuations.test.ts": 7,
+    "server/src/__tests__/run-liveness.test.ts": 11,
+    "server/src/__tests__/runtime-api.test.ts": 6,
+    "server/src/__tests__/sandbox-provider-runtime.test.ts": 9,
+    "server/src/__tests__/secret-provider-registry.test.ts": 6,
+    "server/src/__tests__/secrets-service.test.ts": 3281,
+    "server/src/__tests__/server-info.test.ts": 300,
+    "server/src/__tests__/server-package-build-script.test.ts": 3,
+    "server/src/__tests__/server-startup-feedback-export.test.ts": 27,
+    "server/src/__tests__/shared-telemetry-events.test.ts": 8,
+    "server/src/__tests__/skills-catalog-service.test.ts": 39,
+    "server/src/__tests__/source-trust.test.ts": 2204,
+    "server/src/__tests__/static-index-html.test.ts": 28,
+    "server/src/__tests__/storage-local-provider.test.ts": 23,
+    "server/src/__tests__/task-watchdogs-classifier.test.ts": 9,
+    "server/src/__tests__/task-watchdogs-scheduler.test.ts": 3245,
+    "server/src/__tests__/teams-catalog-install-no-overrides.test.ts": 2995,
+    "server/src/__tests__/teams-catalog-service.test.ts": 75,
+    "server/src/__tests__/telemetry-client-flush.test.ts": 12,
+    "server/src/__tests__/trust-preset-resolver.test.ts": 10,
+    "server/src/__tests__/trust-proxy.test.ts": 11,
+    "server/src/__tests__/ui-branding.test.ts": 6,
+    "server/src/__tests__/version.test.ts": 11,
+    "server/src/__tests__/vite-html-renderer.test.ts": 6,
+    "server/src/__tests__/work-products.test.ts": 6,
+    "server/src/__tests__/work-timeline-service.test.ts": 2541,
+    "server/src/__tests__/workspace-runtime.test.ts": 28685,
+    "server/src/__tests__/worktree-config.test.ts": 29,
+    "server/src/adapters/claude-agent-id-header.test.ts": 6,
+    "server/src/adapters/http/execute.test.ts": 7,
+    "server/src/middleware/cloud-tenant-actor.test.ts": 10,
+    "server/src/services/adapter-models-env.test.ts": 5,
+    "server/src/services/adapter-registry-bootstrap.reconcile.test.ts": 7,
+    "server/src/services/adapter-registry-bootstrap.test.ts": 7,
+    "server/src/services/environment-custom-image-terminal-sessions.test.ts": 11,
+    "server/src/services/execution-allowlist.test.ts": 6,
+    "server/src/services/execution-policy-bootstrap.test.ts": 15,
+    "server/src/services/heartbeat-run-runtime-status.test.ts": 9,
+    "server/src/services/heartbeat-stop-metadata.test.ts": 6,
+    "server/src/services/issue-thread-interactions.test.ts": 757,
+    "server/src/services/recovery/model-profile-hint.test.ts": 4,
+    "server/src/services/recovery/service.pause-durability.test.ts": 4,
+    "server/src/services/recovery/successful-run-handoff.test.ts": 10,
+    "server/src/services/responsible-user-denial-run-outcomes.test.ts": 8,
+    "server/src/services/routines-formatter-cache.test.ts": 1029,
+    "server/src/services/run-scratch.test.ts": 16,
+    "server/src/services/session-workspace-cwd.test.ts": 4
+  }
+}
diff --git a/scripts/general-server-shard.mjs b/scripts/general-server-shard.mjs
new file mode 100644
index 0000000000..16ff2165f9
--- /dev/null
+++ b/scripts/general-server-shard.mjs
@@ -0,0 +1,75 @@
+import { readFileSync } from "node:fs";
+
+// Fallback weight (ms) when the duration manifest is missing or empty.
+const FALLBACK_SUITE_WEIGHT_MS = 1000;
+
+// Loads the per-suite duration manifest produced from a real PR run (see the
+// $comment field in scripts/general-server-shard-durations.json). Returns an
+// empty map on any read/parse problem so sharding degrades to uniform weights
+// instead of failing the test lane.
+export function loadShardDurations(manifestPath) {
+  let parsed;
+  try {
+    parsed = JSON.parse(readFileSync(manifestPath, "utf8"));
+  } catch {
+    return {};
+  }
+
+  const durations = parsed?.durations;
+  if (!durations || typeof durations !== "object" || Array.isArray(durations)) {
+    return {};
+  }
+
+  const result = {};
+  for (const [file, ms] of Object.entries(durations)) {
+    if (typeof ms === "number" && Number.isFinite(ms) && ms >= 0) {
+      result[file] = ms;
+    }
+  }
+  return result;
+}
+
+// Weight assigned to suites absent from the manifest (new or renamed files).
+// The median keeps one unknown suite from skewing a shard the way a mean
+// dragged up by a few 30s+ suites would.
+export function defaultSuiteWeight(durations) {
+  const values = Object.values(durations).sort((a, b) => a - b);
+  if (values.length === 0) {
+    return FALLBACK_SUITE_WEIGHT_MS;
+  }
+  const mid = Math.floor(values.length / 2);
+  return values.length % 2 === 1 ? values[mid] : (values[mid - 1] + values[mid]) / 2;
+}
+
+// Deterministic longest-processing-time partition: heaviest suite first, each
+// assigned to the currently lightest shard. Ties break by file path and then
+// by shard index, so every runner in the matrix computes the identical
+// partition from the same checkout — that invariant is what makes the shards
+// a complete, non-overlapping cover of the suite set.
+export function partitionGeneralServerSuites(files, shardCount, durations = {}) {
+  const fallbackWeight = defaultSuiteWeight(durations);
+  const weighted = files
+    .map((file) => ({ file, weight: durations[file] ?? fallbackWeight }))
+    .sort((a, b) => b.weight - a.weight || a.file.localeCompare(b.file));
+
+  const shards = Array.from({ length: shardCount }, () => ({ files: [], totalWeight: 0 }));
+  for (const { file, weight } of weighted) {
+    let target = 0;
+    for (let index = 1; index < shards.length; index += 1) {
+      if (shards[index].totalWeight < shards[target].totalWeight) {
+        target = index;
+      }
+    }
+    shards[target].files.push(file);
+    shards[target].totalWeight += weight;
+  }
+
+  for (const shard of shards) {
+    shard.files.sort((a, b) => a.localeCompare(b));
+  }
+  return shards;
+}
+
+export function selectGeneralServerShard(files, shardIndex, shardCount, durations = {}) {
+  return partitionGeneralServerSuites(files, shardCount, durations)[shardIndex].files;
+}
diff --git a/scripts/run-vitest-stable.mjs b/scripts/run-vitest-stable.mjs
index 69cca3b188..d37ee4d405 100644
--- a/scripts/run-vitest-stable.mjs
+++ b/scripts/run-vitest-stable.mjs
@@ -3,8 +3,14 @@ import { spawnSync } from "node:child_process";
 import { mkdirSync, mkdtempSync, readdirSync, statSync } from "node:fs";
 import os from "node:os";
 import path from "node:path";
+import { fileURLToPath } from "node:url";
+import { loadShardDurations, selectGeneralServerShard } from "./general-server-shard.mjs";
 
 const repoRoot = process.cwd();
+const scriptsDir = path.dirname(fileURLToPath(import.meta.url));
+const generalServerShardDurations = loadShardDurations(
+  path.join(scriptsDir, "general-server-shard-durations.json"),
+);
 const serverRoot = path.join(repoRoot, "server");
 const serverSrcDir = path.join(repoRoot, "server", "src");
 const serverTestsDir = path.join(repoRoot, "server", "src", "__tests__");
@@ -288,8 +294,11 @@ function runProjectGroup(projects, groupName) {
 function runGeneralGroup(routeTests, groupName, shardIndex = null, shardCount = null) {
   if (groupName === generalServerGroupName) {
     if (shardCount !== null && shardCount > 1) {
-      const shardFiles = generalServerTestFiles.filter(
-        (_, index) => index % shardCount === shardIndex,
+      const shardFiles = selectGeneralServerShard(
+        generalServerTestFiles,
+        shardIndex,
+        shardCount,
+        generalServerShardDurations,
       );
       console.log(
         `\n[test:run] general-server shard ${shardIndex + 1}/${shardCount} running ${shardFiles.length} of ${generalServerTestFiles.length} suites`,
@@ -369,6 +378,8 @@ const routeTests = walk(serverTestsDir)
 // dedicated serialized shards. Sharding this list across runners is what keeps
 // the general-server lane from becoming the PR critical path: the server vitest
 // config pins maxWorkers to 1, so the only way to parallelize is across jobs.
+// Suites are partitioned by recorded duration (scripts/general-server-shard.mjs)
+// rather than round-robin, so one slow suite cluster can't stretch a single shard.
 const generalServerTestFiles = walk(serverSrcDir)
   .map((file) => toRepoPath(file))
   .filter((repoPath) => repoPath.endsWith(".test.ts"))
@@ -396,8 +407,11 @@ if (options.dryRun) {
           options.mode === generalModeName &&
           options.group === generalServerGroupName &&
           options.shardCount !== null
-            ? generalServerTestFiles.filter(
-                (_, index) => index % options.shardCount === options.shardIndex,
+            ? selectGeneralServerShard(
+                generalServerTestFiles,
+                options.shardIndex,
+                options.shardCount,
+                generalServerShardDurations,
               )
             : null,
       },
diff --git a/server/src/__tests__/heartbeat-issue-rewake-throttle.test.ts b/server/src/__tests__/heartbeat-issue-rewake-throttle.test.ts
index 637512f399..2d044de81c 100644
--- a/server/src/__tests__/heartbeat-issue-rewake-throttle.test.ts
+++ b/server/src/__tests__/heartbeat-issue-rewake-throttle.test.ts
@@ -74,19 +74,31 @@ describeEmbeddedPostgres("heartbeat issue rewake throttle", () => {
       if (!runs.some((run) => run.status === "queued" || run.status === "running")) break;
       await new Promise((resolve) => setTimeout(resolve, 50));
     }
-    await db.delete(environmentLeases);
-    await db.delete(issueComments);
-    await db.delete(issues);
-    await db.delete(heartbeatRunEvents);
-    await db.delete(activityLog);
-    await db.delete(heartbeatRuns);
-    await db.delete(agentWakeupRequests);
-    await db.delete(agentRuntimeState);
-    await db.delete(agents);
-    await db.delete(environments);
-    await db.delete(executionWorkspaces);
-    await db.delete(companySkills);
-    await db.delete(companies);
+    // Post-run bookkeeping (run-event records, follow-up wake scheduling) can
+    // still write for a moment after a run reaches a terminal status, so a
+    // single delete sweep can hit a foreign-key violation when a late insert
+    // lands between two deletes. Retry the sweep until it goes through clean.
+    for (let attempt = 0; ; attempt += 1) {
+      try {
+        await db.delete(environmentLeases);
+        await db.delete(issueComments);
+        await db.delete(issues);
+        await db.delete(heartbeatRunEvents);
+        await db.delete(activityLog);
+        await db.delete(heartbeatRuns);
+        await db.delete(agentWakeupRequests);
+        await db.delete(agentRuntimeState);
+        await db.delete(agents);
+        await db.delete(environments);
+        await db.delete(executionWorkspaces);
+        await db.delete(companySkills);
+        await db.delete(companies);
+        break;
+      } catch (error) {
+        if (attempt >= 4) throw error;
+        await new Promise((resolve) => setTimeout(resolve, 100));
+      }
+    }
   });
 
   afterAll(async () => {