feat(models): numbered OpenCode credential selection, labels, migration

Adopt the numbered OPENCODE_API_KEY_N scheme in the model picker and
concurrency surfaces.

- model-select: numeric sort of opencode-<n> keys (#2 before #10); friendly
  OpenCode #N labels (raw opencode-N/<model> value still selected/persisted);
  migrateLegacyModelName rewrites opencode/<model> -> opencode-1/<model>.
- ModelSelector: renders friendly key labels; surfaces a disappeared saved
  credential as UNAVAILABLE (disabled option + notice) without silently
  switching to another model.
- app store: DEFAULT_MODEL -> opencode-1/...; catalogs no longer auto-fallback
  the active model when the selected credential is absent; boot restore
  migrates persisted legacy opencode/<model> tab models idempotently.
- concurrency: providerLabel renders opencode-<n> as OpenCode #<n> in the
  limit rows and Add dropdown (raw provider id preserved on the wire).
- Tests: parsing/sorting/labels/migration, unavailable-state selector behavior,
  no-silent-fallback, and concurrency provider label; fixtures updated to the
  numbered scheme.

Verification: bun install, bun run typecheck (0 errors), bun run test
(1179 passed), bun run check (clean, exit 0), bun run build (vite OK).

5 files changed, 42 insertions, 10 deletions

diff --git a/src/features/concurrency/logic/view-model.test.ts b/src/features/concurrency/logic/view-model.test.ts
index 6e6b770..9c557f5 100644
--- a/src/features/concurrency/logic/view-model.test.ts
+++ b/src/features/concurrency/logic/view-model.test.ts
@@ -13,6 +13,7 @@ import {
   parseLimitInput,
   pauseLabel,
   providerFromModel,
+  providerLabel,
   providerOptions,
   statusLabel,
   summarizeLimits,
@@ -95,7 +96,7 @@ describe("cooldownLabel", () => {
 describe("providerFromModel", () => {
   it("takes the part before the first slash", () => {
     expect(providerFromModel("openai/gpt-4o")).toBe("openai");
-    expect(providerFromModel("openai-compat/gpt-4o-mini")).toBe("openai-compat");
+    expect(providerFromModel("opencode-1/gpt-4o-mini")).toBe("opencode-1");
   });
   it("returns the whole string when there is no slash", () => {
     expect(providerFromModel("umans")).toBe("umans");
@@ -127,6 +128,23 @@ describe("providerOptions", () => {
   });
 });
 
+describe("providerLabel", () => {
+  it("labels a numbered OpenCode provider as OpenCode #N", () => {
+    expect(providerLabel("opencode-2")).toBe("OpenCode #2");
+    expect(providerLabel("opencode-10")).toBe("OpenCode #10");
+  });
+
+  it("leaves non-OpenCode provider ids unchanged", () => {
+    expect(providerLabel("umans")).toBe("umans");
+    expect(providerLabel("anthropic")).toBe("anthropic");
+  });
+
+  it("rejects noncanonical numbered ids (label passthrough)", () => {
+    expect(providerLabel("opencode")).toBe("opencode");
+    expect(providerLabel("opencode-0")).toBe("opencode-0");
+  });
+});
+
 // ── pauseLabel + formatPauseDuration ───────────────────────────────────────────
 
 describe("formatPauseDuration", () => {
@@ -450,12 +468,12 @@ describe("normalizeConcurrencyLimits", () => {
     const limits = normalizeConcurrencyLimits({
       limits: [
         { providerId: "umans", limit: 4 },
-        { providerId: "openai-compat", limit: 5 },
+        { providerId: "opencode-1", limit: 5 },
       ],
     });
     expect(limits).toEqual([
       { providerId: "umans", limit: 4 },
-      { providerId: "openai-compat", limit: 5 },
+      { providerId: "opencode-1", limit: 5 },
     ]);
   });
 
@@ -510,7 +528,7 @@ describe("normalizeConcurrencyStatus", () => {
       providers: [
         { providerId: "umans", limit: 4, inFlight: 2, queued: 1, paused: false },
         {
-          providerId: "openai-compat",
+          providerId: "opencode-1",
           limit: 5,
           inFlight: 5,
           queued: 3,
@@ -532,7 +550,7 @@ describe("normalizeConcurrencyStatus", () => {
     });
     expect(first !== undefined && !("pausedUntil" in first)).toBe(true);
     expect(second).toEqual({
-      providerId: "openai-compat",
+      providerId: "opencode-1",
       limit: 5,
       inFlight: 5,
       queued: 3,
diff --git a/src/features/concurrency/logic/view-model.ts b/src/features/concurrency/logic/view-model.ts
index 8a37198..80c155c 100644
--- a/src/features/concurrency/logic/view-model.ts
+++ b/src/features/concurrency/logic/view-model.ts
@@ -170,6 +170,18 @@ export function providerOptions(
   return out;
 }
 
+/**
+ * Friendly display label for a concurrency provider id. A numbered OpenCode
+ * provider (`opencode-<n>`) renders as "OpenCode #<n>" (so "opencode-2" reads
+ * as a coherent credential identity, matching the model picker); any other id is
+ * shown unchanged. The RAW id is still what is sent to / displayed-with the
+ * backend — this only affects presentation.
+ */
+export function providerLabel(providerId: string): string {
+  const m = /^opencode-([1-9][0-9]*)$/.exec(providerId);
+  return m === null ? providerId : `OpenCode #${m[1]}`;
+}
+
 // ── Status → display view ──────────────────────────────────────────────────────
 
 const NO_LIMITS = "No limits configured";
diff --git a/src/features/concurrency/ui/ConcurrencyLimitRow.svelte b/src/features/concurrency/ui/ConcurrencyLimitRow.svelte
index bf06ac0..c8f6c8f 100644
--- a/src/features/concurrency/ui/ConcurrencyLimitRow.svelte
+++ b/src/features/concurrency/ui/ConcurrencyLimitRow.svelte
@@ -4,6 +4,7 @@
     DEFAULT_COOLDOWN_MS,
     parseCooldownInput,
     parseLimitInput,
+    providerLabel,
     statusLabel,
     type Badge,
     type ConcurrencyLimitView,
@@ -132,8 +133,8 @@
        the buttons never wrap; tight gap + narrow inputs keep the provider name
        visible; the provider shrinks via flex-1 + min-w-0). -->
   <div class="flex flex-nowrap items-center gap-1">
-    <span class="min-w-0 flex-1 truncate font-medium font-mono" title={limit.providerId}
-      >{limit.providerId}</span
+    <span class="min-w-0 flex-1 truncate font-medium" title={limit.providerId}
+      >{providerLabel(limit.providerId)}</span
     >
     <input
       type="text"
diff --git a/src/features/concurrency/ui/ConcurrencyView.svelte b/src/features/concurrency/ui/ConcurrencyView.svelte
index aadb8d1..2e23f5c 100644
--- a/src/features/concurrency/ui/ConcurrencyView.svelte
+++ b/src/features/concurrency/ui/ConcurrencyView.svelte
@@ -6,6 +6,7 @@
     DEFAULT_COOLDOWN_MS,
     parseCooldownInput,
     parseLimitInput,
+    providerLabel,
     providerOptions,
     summarizeLimits,
     viewConcurrencyLimits,
@@ -376,7 +377,7 @@
               <option value="" disabled>No providers available</option>
             {:else}
               {#each providerOpts as provider (provider)}
-                <option value={provider}>{provider}</option>
+                <option value={provider}>{providerLabel(provider)}</option>
               {/each}
             {/if}
           </select>
diff --git a/src/features/concurrency/ui/ConcurrencyView.test.ts b/src/features/concurrency/ui/ConcurrencyView.test.ts
index a8163c2..e214692 100644
--- a/src/features/concurrency/ui/ConcurrencyView.test.ts
+++ b/src/features/concurrency/ui/ConcurrencyView.test.ts
@@ -11,8 +11,8 @@ import type {
 } from "../logic/types";
 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;
+// Available models → provider ids are "umans", "anthropic", "opencode-1".
+const MODELS = ["umans/umans-glm-5.2", "anthropic/claude-sonnet", "opencode-1/gpt-4o"] as const;
 
 // A status entry factory (defaults to a healthy limited provider). The new
 // concurrency-fixes fields (`cooldownMs`, `autoReduced`) are always present.