feat(concurrency): configurable cooldown + adaptive-headroom auto-reduce banner

Consumes the backend's concurrency-fixes (commit 2d27666) — additive to
[email protected], NO version bump. ConcurrencyStatusEntry gains
cooldownMs / autoReduced / autoReducedFrom? / notice?; new
ConcurrencyCooldownResponse / SetConcurrencyCooldownRequest + GET/PUT
/concurrency/cooldown/:providerId.

FE:
- Pure core (logic/view-model.ts): DEFAULT_COOLDOWN_MS; parseCooldownInput
  (non-negative int — 0 is valid, unlike the limit); normalizeCooldown;
  cooldownLabel ("350ms"/"1.2s"/"0ms (off)"); viewConcurrencyStatus extended
  (cooldown + autoReduce fields; auto-reduce → warning badge, not busy);
  viewAutoReduce/autoReduceNotices (banner view — prefers backend notice,
  synthesizes a fallback); summarizeStatus "N auto-reduced" fragment;
  normalizeConcurrencyStatus coerces new fields (immutable readonly build;
  autoReducedFrom/notice only when autoReduced===true); normalizeConcurrencyCooldown.
- Types (logic/types.ts): re-export the 2 new contract types +
  ConcurrencyCooldownResult + Get/SaveConcurrencyCooldown ports.
- UI: ConcurrencyCooldownRow.svelte (inline-edit cooldown + Save → PUT, seeded
  via the ChatLimitField pattern); AutoReduceBanner.svelte (dismissible banner —
  backend notice + "Was N, now M." + "Restore to N"); ConcurrencyView renders
  the cooldown per status card + the banner section. The banner persists while
  autoReduced===true, is dismissible, and clears automatically once a poll shows
  autoReduced===false after a restore PUT.
- Store (store.svelte.ts): getConcurrencyCooldown + setConcurrencyCooldown
  (surface 400/404/503 as ok:false; normalize at the seam) + interface decls.
- App.svelte: saveConcurrencyCooldown adapter → ConcurrencyView.
- Tests: +47 (view-model cooldown/auto-reduce/normalizers; component banner
  render, cooldown PUT, restore clears banner, dismiss; store cooldown GET/PUT).

Re-synced the file: dep (bun install) + re-mirrored .dispatch/transport-contract.
reference.md. typecheck 0/0, 1048 tests green (run twice), biome clean, build OK.

Worktree env: an untracked dispatch-backend → backend symlink was created in the
worktree parent so the canonical file:../dispatch-backend/... paths resolve
(NOT committed — per the §2d/§2j worktree convention).

4 files changed, 560 insertions, 60 deletions

diff --git a/src/features/concurrency/ui/AutoReduceBanner.svelte b/src/features/concurrency/ui/AutoReduceBanner.svelte
new file mode 100644
index 0000000..132ebc7
--- /dev/null
+++ b/src/features/concurrency/ui/AutoReduceBanner.svelte
@@ -0,0 +1,81 @@
+<script lang="ts">
+  import type { AutoReduceNotice } from "../logic/view-model";
+  import type { RestoreOutcome } from "../logic/types";
+
+  let {
+    notice,
+    onRestore,
+    onDismiss,
+  }: {
+    /** The auto-reduce banner view (providerId + message + from/current limit). */
+    notice: AutoReduceNotice;
+    /**
+     * "Restore to N" — PUT the limit back to `fromLimit`. Returns the outcome so
+     * a FAILED restore surfaces an inline error here (the banner owns its error
+     * display; the parent only refreshes on success).
+     */
+    onRestore: (providerId: string, limit: number) => Promise<RestoreOutcome>;
+    /** Hide this banner locally (persists hidden while autoReduced stays true). */
+    onDismiss: (providerId: string) => void;
+  } = $props();
+
+  let restoring = $state(false);
+  /** Inline restore error (e.g. "Concurrency service not available"); cleared on retry. */
+  let error = $state<string | null>(null);
+
+  async function handleRestore(): Promise<void> {
+    restoring = true;
+    error = null;
+    // The parent PUTs the limit + refreshes status on success; the banner clears
+    // once the next poll shows autoReduced===false. On failure the outcome is
+    // bubbled back here so the error shows inline next to the button.
+    const result = await onRestore(notice.providerId, notice.fromLimit);
+    restoring = false;
+    if (!result.ok) {
+      error = result.error;
+    }
+  }
+</script>
+
+<div
+  class="alert alert-warning flex flex-col gap-2 py-2 text-xs"
+  role="status"
+  data-testid={`auto-reduce-banner-${notice.providerId}`}
+>
+  <div class="flex items-start gap-2">
+    <span class="shrink-0">⚠</span>
+    <div class="flex-1">
+      <p>{notice.message}</p>
+      <p class="opacity-70">
+        Was {notice.fromLimit}, now {notice.currentLimit}.
+      </p>
+    </div>
+    <div class="flex shrink-0 items-center gap-1">
+      <!-- The "Restore to N" text stays visible while loading (only the spinner is
+           prepended) so the button keeps its accessible name during the PUT — a
+           spinner-only button loses its name for screen-reader users. -->
+      <button
+        type="button"
+        class="btn btn-warning btn-xs gap-1"
+        disabled={restoring}
+        onclick={handleRestore}
+      >
+        {#if restoring}
+          <span class="loading loading-spinner loading-xs"></span>
+        {/if}
+        Restore to {notice.fromLimit}
+      </button>
+      <button
+        type="button"
+        class="btn btn-ghost btn-xs"
+        aria-label={`Dismiss auto-reduce notice for ${notice.providerId}`}
+        onclick={() => onDismiss(notice.providerId)}
+      >
+        ✕
+      </button>
+    </div>
+  </div>
+  {#if error}
+    <p class="font-mono text-error" data-testid={`restore-error-${notice.providerId}`}>{error}</p>
+  {/if}
+</div>
diff --git a/src/features/concurrency/ui/ConcurrencyCooldownRow.svelte b/src/features/concurrency/ui/ConcurrencyCooldownRow.svelte
new file mode 100644
index 0000000..03ddec9
--- /dev/null
+++ b/src/features/concurrency/ui/ConcurrencyCooldownRow.svelte
@@ -0,0 +1,93 @@
+<script lang="ts">
+  import { untrack } from "svelte";
+  import { parseCooldownInput } from "../logic/view-model";
+  import type { SaveConcurrencyCooldown } from "../logic/types";
+
+  let {
+    providerId,
+    cooldownMs,
+    save,
+  }: {
+    /** The provider this cooldown row controls. */
+    providerId: string;
+    /** The current per-slot release cooldown (ms) from the live status poll. */
+    cooldownMs: number;
+    save: SaveConcurrencyCooldown;
+  } = $props();
+
+  // Inline-edit state: the raw text bound to the cooldown input. Seeded from the
+  // row's canonical cooldownMs, but only while the field is untouched — so a
+  // status-poll refresh re-syncs it without clobbering an in-flight edit. Mirrors
+  // the ConcurrencyLimitRow / ChatLimitField seed pattern.
+  let draft = $state("");
+  let lastSeed = $state("");
+  let saving = $state(false);
+  let error = $state<string | null>(null);
+  /** Brief "Saved." confirmation after a successful save; cleared on edit. */
+  let justSaved = $state(false);
+
+  $effect(() => {
+    const incoming = String(cooldownMs);
+    untrack(() => {
+      if (draft === lastSeed) draft = incoming;
+      lastSeed = incoming;
+    });
+  });
+
+  const parsed = $derived(parseCooldownInput(draft));
+  const dirty = $derived(parsed !== null && parsed !== cooldownMs);
+
+  function onInput(): void {
+    justSaved = false;
+    error = null;
+  }
+
+  async function handleSave(): Promise<void> {
+    if (parsed === null || parsed === cooldownMs) return;
+    saving = true;
+    error = null;
+    const result = await save(providerId, parsed);
+    saving = false;
+    if (result.ok) {
+      // Reflect the echoed cooldown back into the field immediately (the prop
+      // also re-asserts it via the seed effect above once the parent reloads).
+      draft = String(result.cooldownMs);
+      lastSeed = draft;
+      justSaved = true;
+    } else {
+      error = result.error;
+    }
+  }
+</script>
+
+<div class="flex items-center gap-2 text-xs">
+  <span class="opacity-60">cooldown</span>
+  <input
+    type="text"
+    inputmode="numeric"
+    class="input input-bordered input-xs w-20 font-mono"
+    aria-label={`Release cooldown (ms) for ${providerId}`}
+    bind:value={draft}
+    oninput={onInput}
+    disabled={saving}
+  />
+  <span class="opacity-50">ms</span>
+  <button
+    type="button"
+    class="btn btn-primary btn-xs"
+    aria-label={`Save cooldown for ${providerId}`}
+    disabled={!dirty || saving}
+    onclick={handleSave}
+  >
+    {#if saving}
+      <span class="loading loading-spinner loading-xs"></span>
+    {:else}
+      Save
+    {/if}
+  </button>
+  {#if error}
+    <span class="font-mono text-error">{error}</span>
+  {:else if justSaved && !dirty}
+    <span class="text-success">Saved.</span>
+  {/if}
+</div>
diff --git a/src/features/concurrency/ui/ConcurrencyView.svelte b/src/features/concurrency/ui/ConcurrencyView.svelte
index f8a2199..6078b1a 100644
--- a/src/features/concurrency/ui/ConcurrencyView.svelte
+++ b/src/features/concurrency/ui/ConcurrencyView.svelte
@@ -2,6 +2,7 @@
   import { untrack } from "svelte";
   import type { ConcurrencyStatusEntry } from "@dispatch/transport-contract";
   import {
+    autoReduceNotices,
     type Badge,
     parseLimitInput,
     providerOptions,
@@ -15,8 +16,12 @@
     DeleteConcurrencyLimit,
     LoadConcurrencyLimits,
     LoadConcurrencyStatus,
+    RestoreOutcome,
+    SaveConcurrencyCooldown,
     SaveConcurrencyLimit,
   } from "../logic/types";
+  import AutoReduceBanner from "./AutoReduceBanner.svelte";
+  import ConcurrencyCooldownRow from "./ConcurrencyCooldownRow.svelte";
   import ConcurrencyLimitRow from "./ConcurrencyLimitRow.svelte";
 
   let {
@@ -25,6 +30,7 @@
     saveLimit,
     deleteLimit,
     loadStatus,
+    saveCooldown,
   }: {
     /** Available models (`<provider>/<model>`) — the source of provider ids for the Add dropdown. */
     models: readonly string[];
@@ -32,6 +38,7 @@
     saveLimit: SaveConcurrencyLimit;
     deleteLimit: DeleteConcurrencyLimit;
     loadStatus: LoadConcurrencyStatus;
+    saveCooldown: SaveConcurrencyCooldown;
   } = $props();
 
   const badgeClass: Record<Badge, string> = {
@@ -136,6 +143,18 @@
     return result;
   }
 
+  // Wrap the cooldown save so a successful PUT refreshes the live status (which
+  // re-carries the new `cooldownMs`). The row still gets the result to drive its
+  // own UI. `getCooldown` is exposed for completeness/future use (the live status
+  // already carries `cooldownMs`, so the row seeds from the status view).
+  async function cooldownSave(providerId: string, cooldownMs: number) {
+    const result = await saveCooldown(providerId, cooldownMs);
+    if (result.ok) {
+      void refreshStatus();
+    }
+    return result;
+  }
+
   // ── Live status (polls while mounted) ───────────────────────────────────────
   let statusEntries = $state<readonly ConcurrencyStatusEntry[]>([]);
   let statusError = $state<string | null>(null);
@@ -158,6 +177,69 @@
   const statusViews = $derived(viewConcurrencyStatuses(statusEntries, now));
   const statusSummary = $derived(summarizeStatus(statusEntries, now));
 
+  // ── Auto-reduce banners (persist while autoReduced===true; dismissible) ───────
+  //
+  // When a provider's limit is auto-reduced by a 429, `GET /concurrency/status`
+  // carries `autoReduced: true` (+ `autoReducedFrom` + `notice`). We render a
+  // banner per such provider. The banner is DISMISSIBLE: a dismissed provider
+  // stays hidden while it remains auto-reduced (persist-while-true), and is
+  // UN-dismissed the moment a poll shows it no longer auto-reduced — so a future
+  // auto-reduce re-shows the banner. Restoring the limit (PUT) clears
+  // `autoReduced` server-side → the next poll drops the banner automatically.
+  //
+  // The dismissed set is intentionally COMPONENT-LOCAL (NOT persisted to
+  // localStorage / a module-global): it resets on remount (sidebar view switch /
+  // reload). This is correct — `autoReduced` is a REAL persisted degraded state,
+  // so re-showing the banner on a fresh mount reminds the user. Persisting a
+  // dismissal across reloads would risk HIDING an ongoing degradation (a
+  // footgun), and AGENTS.md forbids module-global ambient state. Mirrors the
+  // component-local `limitsError`/`statusError` pattern.
+  let dismissedAutoReduce = $state<ReadonlySet<string>>(new Set());
+
+  const allNotices = $derived(autoReduceNotices(statusEntries));
+  const visibleNotices = $derived(
+    allNotices.filter((n) => !dismissedAutoReduce.has(n.providerId)),
+  );
+
+  // Reconcile the dismissed set against the live auto-reduced providers: keep a
+  // dismissed entry ONLY while its provider is still auto-reduced. A provider
+  // that has been restored (no longer in `allNotices`) is dropped from the
+  // dismissed set so a future auto-reduce re-shows its banner.
+  $effect(() => {
+    const autoReducedIds = new Set(allNotices.map((n) => n.providerId));
+    untrack(() => {
+      let changed = false;
+      const next = new Set<string>();
+      for (const id of dismissedAutoReduce) {
+        if (autoReducedIds.has(id)) next.add(id);
+        else changed = true;
+      }
+      if (changed) dismissedAutoReduce = next;
+    });
+  });
+
+  function dismissAutoReduce(providerId: string): void {
+    if (dismissedAutoReduce.has(providerId)) return;
+    dismissedAutoReduce = new Set([...dismissedAutoReduce, providerId]);
+  }
+
+  // "Restore to N" — PUT the limit back to `autoReducedFrom` via the limits
+  // endpoint (a manual PUT clears `autoReduced` server-side). Refreshes limits +
+  // status on success; the next status poll shows `autoReduced===false` and the
+  // banner drops (the dismissed-set effect above un-dismisses it too). The banner
+  // component owns its own restoring-spinner + inline error; on FAILURE the
+  // outcome is bubbled back so the banner shows the error inline (instead of
+  // silently re-enabling the button / surfacing it only in the limits section).
+  async function restoreLimit(providerId: string, limit: number): Promise<RestoreOutcome> {
+    const result = await saveLimit(providerId, limit);
+    if (result.ok) {
+      void refreshLimits();
+      void refreshStatus();
+      return { ok: true };
+    }
+    return { ok: false, error: result.error };
+  }
+
   async function refreshStatus(): Promise<void> {
     if (statusInFlight) return;
     statusInFlight = true;
@@ -192,6 +274,19 @@
 </script>
 
 <div class="flex flex-col gap-4">
+  <!-- Auto-reduce banners (appear when a provider's limit was auto-reduced by a 429) -->
+  {#if visibleNotices.length > 0}
+    <section class="flex flex-col gap-2" aria-label="Concurrency auto-reduce notices">
+      {#each visibleNotices as notice (notice.providerId)}
+        <AutoReduceBanner
+          {notice}
+          onRestore={restoreLimit}
+          onDismiss={dismissAutoReduce}
+        />
+      {/each}
+    </section>
+  {/if}
+
   <!-- Limits (config) -->
   <section class="flex flex-col gap-2">
     <div class="flex items-center justify-between gap-2">
@@ -319,10 +414,22 @@
             <div class="flex flex-wrap items-center justify-between gap-2 text-xs opacity-70">
               <span title="In-flight slots held vs cap">{s.inFlightLabel} in flight</span>
               <span>{s.queuedLabel}</span>
+              <span title="Per-slot release cooldown">cooldown {s.cooldownLabel}</span>
             </div>
             {#if s.pausedLabel}
               <span class="text-xs text-warning">{s.pausedLabel}</span>
             {/if}
+            {#if s.autoReduced}
+              <span class="text-xs text-warning">
+                Limit auto-reduced{#if s.autoReducedFrom !== null}
+                  from {s.autoReducedFrom} to {s.limit}{/if}.
+              </span>
+            {/if}
+            <ConcurrencyCooldownRow
+              providerId={s.providerId}
+              cooldownMs={s.cooldownMs}
+              save={cooldownSave}
+            />
           </li>
         {/each}
       </ul>
diff --git a/src/features/concurrency/ui/ConcurrencyView.test.ts b/src/features/concurrency/ui/ConcurrencyView.test.ts
index 3dc8e78..854f13b 100644
--- a/src/features/concurrency/ui/ConcurrencyView.test.ts
+++ b/src/features/concurrency/ui/ConcurrencyView.test.ts
@@ -3,6 +3,7 @@ import { render, screen } from "@testing-library/svelte";
 import userEvent from "@testing-library/user-event";
 import { describe, expect, it } from "vitest";
 import type {
+  ConcurrencyCooldownResult,
   ConcurrencyDeleteResult,
   ConcurrencyLimitResult,
   ConcurrencyLimitsResult,
@@ -13,35 +14,80 @@ import ConcurrencyView from "./ConcurrencyView.svelte";
 // Available models → provider ids are "umans", "anthropic", "openai-compat".
 const MODELS = ["umans/umans-glm-5.2", "anthropic/claude-sonnet", "openai-compat/gpt-4o"] as const;
 
-// Fakes for the four injected ports. Each resolves immediately so the mount
-// effect's initial load settles in a microtask (assertions await via findBy*).
+// A status entry factory (defaults to a healthy limited provider). The new
+// concurrency-fixes fields (`cooldownMs`, `autoReduced`) are always present.
+function statusEntry(over: Partial<ConcurrencyStatusEntry> = {}): ConcurrencyStatusEntry {
+  return {
+    providerId: "umans",
+    limit: 4,
+    inFlight: 2,
+    queued: 1,
+    paused: false,
+    cooldownMs: 350,
+    autoReduced: false,
+    ...over,
+  };
+}
 
+// Fakes for the injected ports. Each resolves immediately so the mount effect's
+// initial load settles in a microtask (assertions await via findBy*). The status
+// list is mutable so a test can flip `autoReduced` between polls to simulate a
+// restore clearing the banner.
 function makeFakes(opts?: {
   limits?: readonly { providerId: string; limit: number }[];
-  status?: readonly ConcurrencyStatusEntry[];
+  status?: ConcurrencyStatusEntry[];
+  /**
+   * When set, `saveLimit` rejects with this error (returns `ok: false`) — used
+   * to test the auto-reduce banner's inline restore-error feedback.
+   */
+  saveLimitError?: string;
+  /**
+   * Optional hook invoked inside `saveLimit` AFTER recording the call. Lets a
+   * test simulate a backend side-effect of the PUT (e.g. clearing `autoReduced`
+   * on the next status poll). Receives the providerId + limit + the fakes bag so
+   * it can mutate the status list. (A plain method reassignment would NOT reach
+   * the already-rendered component — the prop captured the original closure.)
+   */
+  onSaveLimit?: (
+    providerId: string,
+    limit: number,
+    self: { calls: MakeFakesCalls; setStatus: (next: ConcurrencyStatusEntry[]) => void },
+  ) => void;
 }) {
   let limits = opts?.limits ?? [{ providerId: "umans", limit: 4 }];
-  const status = opts?.status ?? [
-    { providerId: "umans", limit: 4, inFlight: 2, queued: 1, paused: false },
-  ];
+  let status = opts?.status ?? [statusEntry()];
+  const onSaveLimit = opts?.onSaveLimit;
+  const saveLimitError = opts?.saveLimitError;
 
-  const calls = {
+  const calls: MakeFakesCalls = {
     loadLimits: 0,
     loadStatus: 0,
     saves: [] as { providerId: string; limit: number }[],
     deletes: [] as string[],
+    cooldownSaves: [] as { providerId: string; cooldownMs: number }[],
   };
 
+  function setStatus(next: ConcurrencyStatusEntry[]): void {
+    status = next;
+  }
+
   return {
     calls,
+    // Allow a test to mutate the status list between polls (e.g. clear
+    // autoReduced after a restore to simulate the next poll).
+    setStatus,
     loadLimits: async (): Promise<ConcurrencyLimitsResult> => {
       calls.loadLimits++;
       return { ok: true, limits };
     },
     saveLimit: async (providerId: string, limit: number): Promise<ConcurrencyLimitResult> => {
       calls.saves.push({ providerId, limit });
+      if (saveLimitError !== undefined) {
+        return { ok: false, error: saveLimitError };
+      }
       // Reflect the new limit into the list the next load returns.
       limits = [...limits.filter((l) => l.providerId !== providerId), { providerId, limit }];
+      if (onSaveLimit !== undefined) onSaveLimit(providerId, limit, { calls, setStatus });
       return { ok: true, providerId, limit };
     },
     deleteLimit: async (providerId: string): Promise<ConcurrencyDeleteResult> => {
@@ -53,21 +99,41 @@ function makeFakes(opts?: {
       calls.loadStatus++;
       return { ok: true, providers: status };
     },
+    saveCooldown: async (
+      providerId: string,
+      cooldownMs: number,
+    ): Promise<ConcurrencyCooldownResult> => {
+      calls.cooldownSaves.push({ providerId, cooldownMs });
+      // Reflect the new cooldown into the status list the next load returns.
+      status = status.map((s) => (s.providerId === providerId ? { ...s, cooldownMs } : s));
+      return { ok: true, providerId, cooldownMs };
+    },
+  };
+}
+
+type MakeFakesCalls = {
+  loadLimits: number;
+  loadStatus: number;
+  saves: { providerId: string; limit: number }[];
+  deletes: string[];
+  cooldownSaves: { providerId: string; cooldownMs: number }[];
+};
+
+function props(fakes: ReturnType<typeof makeFakes>) {
+  return {
+    models: MODELS as unknown as readonly string[],
+    loadLimits: fakes.loadLimits,
+    saveLimit: fakes.saveLimit,
+    deleteLimit: fakes.deleteLimit,
+    loadStatus: fakes.loadStatus,
+    saveCooldown: fakes.saveCooldown,
   };
 }
 
 describe("ConcurrencyView", () => {
   it("loads + renders the configured limits and live status on mount", async () => {
     const fakes = makeFakes();
-    render(ConcurrencyView, {
-      props: {
-        models: MODELS,
-        loadLimits: fakes.loadLimits,
-        saveLimit: fakes.saveLimit,
-        deleteLimit: fakes.deleteLimit,
-        loadStatus: fakes.loadStatus,
-      },
-    });
+    render(ConcurrencyView, { props: props(fakes) });
 
     // The provider dropdown is populated from the available models' providers.
     const providerSelect = await screen.findByLabelText("Provider");
@@ -81,21 +147,21 @@ describe("ConcurrencyView", () => {
     expect(fakes.calls.loadStatus).toBeGreaterThanOrEqual(1);
   });
 
+  it("renders the per-provider cooldown label from the live status", async () => {
+    const fakes = makeFakes({ status: [statusEntry({ cooldownMs: 350 })] });
+    render(ConcurrencyView, { props: props(fakes) });
+
+    // The status card shows the cooldown alongside in-flight/queue.
+    expect(await screen.findByText(/cooldown 350ms/)).toBeInTheDocument();
+  });
+
   it("surfaces NO loading indicator during refresh (background poll is silent — no flicker)", async () => {
     // The 2s status poll + post-mutation reloads are SILENT: they never toggle a
     // visible loading state, so the Refresh buttons are plain-text (no spinner)
     // and the list area never reflows mid-refresh. Regression guard for the
     // flicker fix (mirrors the heartbeat runs list).
     const fakes = makeFakes();
-    render(ConcurrencyView, {
-      props: {
-        models: MODELS,
-        loadLimits: fakes.loadLimits,
-        saveLimit: fakes.saveLimit,
-        deleteLimit: fakes.deleteLimit,
-        loadStatus: fakes.loadStatus,
-      },
-    });
+    render(ConcurrencyView, { props: props(fakes) });
 
     await screen.findByText(/1 provider · 2\/4 in flight · 1 queued/);
 
@@ -116,15 +182,7 @@ describe("ConcurrencyView", () => {
   it("adds a provider limit via the dropdown form (calls saveLimit + reloads)", async () => {
     const user = userEvent.setup();
     const fakes = makeFakes({ limits: [], status: [] });
-    render(ConcurrencyView, {
-      props: {
-        models: MODELS,
-        loadLimits: fakes.loadLimits,
-        saveLimit: fakes.saveLimit,
-        deleteLimit: fakes.deleteLimit,
-        loadStatus: fakes.loadStatus,
-      },
-    });
+    render(ConcurrencyView, { props: props(fakes) });
 
     const providerSelect = await screen.findByLabelText("Provider");
     // Choose "anthropic" from the dropdown (the list is auto-selected first).
@@ -142,15 +200,7 @@ describe("ConcurrencyView", () => {
   it("disables Add when the limit is empty/invalid (provider is auto-selected)", async () => {
     const user = userEvent.setup();
     const fakes = makeFakes({ limits: [], status: [] });
-    render(ConcurrencyView, {
-      props: {
-        models: MODELS,
-        loadLimits: fakes.loadLimits,
-        saveLimit: fakes.saveLimit,
-        deleteLimit: fakes.deleteLimit,
-        loadStatus: fakes.loadStatus,
-      },
-    });
+    render(ConcurrencyView, { props: props(fakes) });
 
     const providerSelect = await screen.findByLabelText("Provider");
     // A provider is auto-selected from the dropdown.
@@ -172,13 +222,7 @@ describe("ConcurrencyView", () => {
   it("shows no-providers + disables the dropdown when there are no models", async () => {
     const fakes = makeFakes({ limits: [], status: [] });
     render(ConcurrencyView, {
-      props: {
-        models: [],
-        loadLimits: fakes.loadLimits,
-        saveLimit: fakes.saveLimit,
-        deleteLimit: fakes.deleteLimit,
-        loadStatus: fakes.loadStatus,
-      },
+      props: { ...props(fakes), models: [] as unknown as readonly string[] },
     });
 
     const providerSelect = await screen.findByLabelText("Provider");
@@ -189,15 +233,7 @@ describe("ConcurrencyView", () => {
   it("removes a provider limit via the row ✕ (calls deleteLimit + reloads)", async () => {
     const user = userEvent.setup();
     const fakes = makeFakes();
-    render(ConcurrencyView, {
-      props: {
-        models: MODELS,
-        loadLimits: fakes.loadLimits,
-        saveLimit: fakes.saveLimit,
-        deleteLimit: fakes.deleteLimit,
-        loadStatus: fakes.loadStatus,
-      },
-    });
+    render(ConcurrencyView, { props: props(fakes) });
 
     // Wait for the limits to load (unique summary) before interacting.
     await screen.findByText(/1 limit configured/);
@@ -209,7 +245,7 @@ describe("ConcurrencyView", () => {
 
   it("surfaces a load error from the limits endpoint", async () => {
     const failing = {
-      models: MODELS,
+      models: MODELS as unknown as readonly string[],
       loadLimits: async (): Promise<ConcurrencyLimitsResult> => ({
         ok: false,
         error: "Concurrency service not available",
@@ -217,8 +253,191 @@ describe("ConcurrencyView", () => {
       saveLimit: async (): Promise<ConcurrencyLimitResult> => ({ ok: false, error: "noop" }),
       deleteLimit: async (): Promise<ConcurrencyDeleteResult> => ({ ok: false, error: "noop" }),
       loadStatus: async (): Promise<ConcurrencyStatusResult> => ({ ok: true, providers: [] }),
+      saveCooldown: async (): Promise<ConcurrencyCooldownResult> => ({ ok: false, error: "noop" }),
     };
     render(ConcurrencyView, { props: failing });
     expect(await screen.findByText("Concurrency service not available")).toBeVisible();
   });
+
+  // ── Concurrency-fixes: auto-reduce banner + cooldown editing ────────────────
+
+  it("renders an auto-reduce banner (with the backend notice + Restore) when a provider is auto-reduced", async () => {
+    const fakes = makeFakes({
+      status: [
+        statusEntry({
+          limit: 3,
+          autoReduced: true,
+          autoReducedFrom: 4,
+          notice: "Concurrency limit auto-reduced to 3 after a 429 — restore manually when ready.",
+        }),
+      ],
+    });
+    render(ConcurrencyView, { props: props(fakes) });
+
+    // The banner shows the backend notice verbatim + a "Restore to 4" action.
+    expect(await screen.findByText(/auto-reduced to 3 after a 429/)).toBeVisible();
+    expect(await screen.findByRole("button", { name: /Restore to 4/ })).toBeVisible();
+    // The "Was 4, now 3." provenance line is shown.
+    expect(await screen.findByText(/Was 4, now 3\./)).toBeVisible();
+  });
+
+  it("clears the banner after Restore (next status poll shows autoReduced===false)", async () => {
+    const user = userEvent.setup();
+    // Start auto-reduced (limit 3, was 4). The restore PUT clears `autoReduced`
+    // server-side; the next status poll returns limit 4 + autoReduced===false →
+    // the banner drops.
+    const fakes = makeFakes({
+      status: [
+        statusEntry({
+          limit: 3,
+          autoReduced: true,
+          autoReducedFrom: 4,
+          notice: "Concurrency limit auto-reduced to 3 after a 429.",
+        }),
+      ],
+      onSaveLimit: (_providerId, limit, self) => {
+        // Simulate the backend clearing `autoReduced` on the manual PUT: the next
+        // status load returns the restored limit with autoReduced===false.
+        self.setStatus([statusEntry({ limit, autoReduced: false })]);
+      },
+    });
+    render(ConcurrencyView, { props: props(fakes) });
+
+    const restoreBtn = await screen.findByRole("button", { name: /Restore to 4/ });
+    await user.click(restoreBtn);
+
+    // The restore PUT the limit back to the original (autoReducedFrom = 4).
+    expect(fakes.calls.saves).toEqual([{ providerId: "umans", limit: 4 }]);
+    // The banner is gone (no Restore button, no notice text); the status summary
+    // now reflects the restored limit (2/4 in flight).
+    await screen.findByText(/1 provider · 2\/4 in flight · 1 queued/);
+    expect(screen.queryByRole("button", { name: /Restore to/ })).toBeNull();
+    expect(screen.queryByText(/auto-reduced to 3 after a 429/)).toBeNull();
+  });
+
+  it("dismisses the auto-reduce banner locally while it stays auto-reduced", async () => {
+    const user = userEvent.setup();
+    const fakes = makeFakes({
+      status: [
+        statusEntry({
+          limit: 3,
+          autoReduced: true,
+          autoReducedFrom: 4,
+          notice: "Concurrency limit auto-reduced to 3 after a 429.",
+        }),
+      ],
+    });
+    render(ConcurrencyView, { props: props(fakes) });
+
+    await screen.findByRole("button", { name: /Restore to 4/ });
+    // Dismiss the banner (hide locally — the provider is still auto-reduced).
+    await user.click(screen.getByLabelText("Dismiss auto-reduce notice for umans"));
+    expect(screen.queryByRole("button", { name: /Restore to/ })).toBeNull();
+    expect(screen.queryByText(/auto-reduced to 3 after a 429/)).toBeNull();
+  });
+
+  it("shows an inline error in the banner when the Restore PUT fails (no silent re-enable)", async () => {
+    const user = userEvent.setup();
+    const fakes = makeFakes({
+      status: [
+        statusEntry({
+          limit: 3,
+          autoReduced: true,
+          autoReducedFrom: 4,
+          notice: "Concurrency limit auto-reduced to 3 after a 429.",
+        }),
+      ],
+      saveLimitError: "Concurrency service not available",
+    });
+    render(ConcurrencyView, { props: props(fakes) });
+
+    const restoreBtn = await screen.findByRole("button", { name: /Restore to 4/ });
+    await user.click(restoreBtn);
+
+    // The error surfaces INLINE in the banner (near the restore action), not
+    // only in the far-away limits section. The banner is still present (restore
+    // did not succeed) and the button re-enabled for a retry.
+    expect(await screen.findByTestId("restore-error-umans")).toHaveTextContent(
+      "Concurrency service not available",
+    );
+    expect(screen.getByRole("button", { name: /Restore to 4/ })).toBeVisible();
+    expect(screen.getByRole("button", { name: /Restore to 4/ })).not.toBeDisabled();
+    // The restore PUT was attempted.
+    expect(fakes.calls.saves).toEqual([{ providerId: "umans", limit: 4 }]);
+  });
+
+  it("clears the inline restore error on a retry that succeeds", async () => {
+    const user = userEvent.setup();
+    // First restore fails; the second succeeds (clears autoReduced). Reassigning
+    // `fakes.saveLimit` BEFORE `props(fakes)` is captured would NOT reach the
+    // rendered component, so swap it BEFORE render here.
+    const fakes = makeFakes({
+      status: [
+        statusEntry({
+          limit: 3,
+          autoReduced: true,
+          autoReducedFrom: 4,
+          notice: "Concurrency limit auto-reduced to 3 after a 429.",
+        }),
+      ],
+      onSaveLimit: (_providerId, limit, self) => {
+        self.setStatus([statusEntry({ limit, autoReduced: false })]);
+      },
+    });
+    let attempts = 0;
+    const succeeding = fakes.saveLimit;
+    fakes.saveLimit = async (providerId, limit) => {
+      attempts++;
+      if (attempts === 1) return { ok: false, error: "Concurrency service not available" };
+      return succeeding(providerId, limit);
+    };
+    render(ConcurrencyView, { props: props(fakes) });
+
+    const restoreBtn = await screen.findByRole("button", { name: /Restore to 4/ });
+    await user.click(restoreBtn);
+    // First attempt: inline error appears.
+    expect(await screen.findByTestId("restore-error-umans")).toBeInTheDocument();
+
+    // Retry: the error clears, the banner drops (restore succeeded).
+    await user.click(screen.getByRole("button", { name: /Restore to 4/ }));
+    await screen.findByText(/1 provider · 2\/4 in flight · 1 queued/);
+    expect(screen.queryByTestId("restore-error-umans")).toBeNull();
+    expect(screen.queryByRole("button", { name: /Restore to/ })).toBeNull();
+  });
+
+  it("edits the per-provider cooldown (PUT /concurrency/cooldown + reloads status)", async () => {
+    const user = userEvent.setup();
+    const fakes = makeFakes({ status: [statusEntry({ cooldownMs: 350 })] });
+    render(ConcurrencyView, { props: props(fakes) });
+
+    // Wait for the status card + its cooldown input (seeded with 350).
+    const cooldownInput = await screen.findByLabelText("Release cooldown (ms) for umans");
+    expect((cooldownInput as HTMLInputElement).value).toBe("350");
+
+    await user.clear(cooldownInput);
+    await user.type(cooldownInput, "500");
+    await user.click(screen.getByRole("button", { name: "Save cooldown for umans" }));
+
+    // The cooldown PUT fired with the new value.
+    expect(fakes.calls.cooldownSaves).toEqual([{ providerId: "umans", cooldownMs: 500 }]);
+    // After save the component reloads status (which now carries cooldownMs=500).
+    expect(await screen.findByText(/cooldown 500ms/)).toBeInTheDocument();
+  });
+
+  it("rejects a negative cooldown input (Save disabled — non-negative integer only)", async () => {
+    const user = userEvent.setup();
+    const fakes = makeFakes({ status: [statusEntry({ cooldownMs: 350 })] });
+    render(ConcurrencyView, { props: props(fakes) });
+
+    const cooldownInput = await screen.findByLabelText("Release cooldown (ms) for umans");
+    // 0 is valid (no cooldown); a negative is not.
+    await user.clear(cooldownInput);
+    await user.type(cooldownInput, "0");
+    expect(screen.getByRole("button", { name: "Save cooldown for umans" })).toBeEnabled();
+
+    await user.clear(cooldownInput);
+    await user.type(cooldownInput, "-5");
+    expect(screen.getByRole("button", { name: "Save cooldown for umans" })).toBeDisabled();
+    expect(fakes.calls.cooldownSaves).toHaveLength(0);
+  });
 });