Add Claude Fable 5 to the model catalog (#1443)

* Add Claude Fable 5 to the model catalog

Fable 5 (`claude-fable-5`) is the new top-tier Claude model above Opus,
but the Claude provider's model list is hardcoded in `CLAUDE_MODELS` and
was not fetched dynamically, so it never appeared in the selector.

- Add `claude-fable-5` to `CLAUDE_MODELS` (non-default; Opus 4.8 stays the
  default). Uses the Opus extended-thinking effort levels (low/medium/high/
  xhigh/max). No `[1m]` variant: Fable 5 is natively 1M context, unlike the
  Opus/Sonnet entries whose `[1m]` opts a 200K-default model into 1M.
- Teach `normalizeClaudeRuntimeModelId` the Fable family. Its version is a
  single segment (`fable-5`) rather than the `{major}-{minor}` scheme, so it
  needs its own match to map dated runtime IDs back to the catalog ID.
- Update the model-list and normalization test expectations, plus the CLI
  provider e2e catalog fixture.

Fast Mode is correctly unaffected — its allowlist is Opus 4.6/4.7/4.8 only.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* Simplify Fable runtime-ID normalization

Drop the unused `[1m]` capture from the Fable match branch. There is no
`claude-fable-5[1m]` catalog entry — Fable 5 is natively 1M context, so
there is no 200K-default model to opt into 1M — which made that path dead
code (and an untested one). Keep the `[-_ ]+` separator class for
consistency with the sibling opus/sonnet/haiku regex right below it.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: lumingjun <lumingjun@bytedance.com>
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

packages/cli/tests/15-provider.test.ts

@@ -45,6 +45,11 @@ interface ProviderListRow {
 }
 
 const EXPECTED_CLAUDE_MODELS = [
+  {
+    id: "claude-fable-5",
+    model: "Fable 5",
+    descriptionFragment: "Most powerful",
+  },
   {
     id: "claude-opus-4-8[1m]",
     model: "Opus 4.8 1M",

packages/server/src/server/agent/providers/claude/agent.test.ts

@@ -408,6 +408,7 @@ describe("ClaudeAgentClient.listModels", () => {
       const models = await client.listModels({ cwd: "/tmp/claude-models", force: false });
 
       expect(models.map((m) => m.id)).toEqual([
+        "claude-fable-5",
         "claude-opus-4-8[1m]",
         "claude-opus-4-8",
         "claude-opus-4-7[1m]",

packages/server/src/server/agent/providers/claude/models.test.ts

@@ -35,6 +35,7 @@ describe("getClaudeModels", () => {
   it("returns all claude models", () => {
     const models = getClaudeModels();
     expect(models.map((m) => m.id)).toEqual([
+      "claude-fable-5",
       "claude-opus-4-8[1m]",
       "claude-opus-4-8",
       "claude-opus-4-7[1m]",
@@ -179,6 +180,7 @@ describe("ClaudeAgentClient.listModels", () => {
 
 describe("normalizeClaudeRuntimeModelId", () => {
   it("returns exact match for known model IDs", () => {
+    expect(normalizeClaudeRuntimeModelId("claude-fable-5")).toBe("claude-fable-5");
     expect(normalizeClaudeRuntimeModelId("claude-opus-4-6")).toBe("claude-opus-4-6");
     expect(normalizeClaudeRuntimeModelId("claude-opus-4-6[1m]")).toBe("claude-opus-4-6[1m]");
     expect(normalizeClaudeRuntimeModelId("claude-sonnet-4-6")).toBe("claude-sonnet-4-6");
@@ -186,6 +188,7 @@ describe("normalizeClaudeRuntimeModelId", () => {
   });
 
   it("normalizes dated model IDs to base model", () => {
+    expect(normalizeClaudeRuntimeModelId("claude-fable-5-20260301")).toBe("claude-fable-5");
     expect(normalizeClaudeRuntimeModelId("claude-opus-4-6-20260101")).toBe("claude-opus-4-6");
     expect(normalizeClaudeRuntimeModelId("claude-sonnet-4-6-20260101")).toBe("claude-sonnet-4-6");
     expect(normalizeClaudeRuntimeModelId("claude-haiku-4-5-20251001")).toBe("claude-haiku-4-5");

packages/server/src/server/agent/providers/claude/models.ts

@@ -21,6 +21,13 @@ const CLAUDE_OPUS_EXTENDED_THINKING_OPTIONS = [
 ] as const;
 
 const CLAUDE_MODELS: AgentModelDefinition[] = [
+  {
+    provider: "claude",
+    id: "claude-fable-5",
+    label: "Fable 5",
+    description: "Fable 5 · Most powerful model",
+    thinkingOptions: [...CLAUDE_OPUS_EXTENDED_THINKING_OPTIONS],
+  },
   {
     provider: "claude",
     id: "claude-opus-4-8[1m]",
@@ -206,6 +213,15 @@ export function normalizeClaudeRuntimeModelId(value: string | null | undefined):
     return trimmed;
   }
 
+  // Fable uses a single-segment version (claude-fable-5), not the {major}-{minor}
+  // scheme of opus/sonnet/haiku, so match it separately. This maps dated runtime
+  // strings (e.g. claude-fable-5-20260301) back to the catalog ID. No [1m] variant:
+  // Fable 5 is natively 1M, so there is no 200K-default model to opt into 1M.
+  const fableMatch = trimmed.match(/(?:claude-)?fable[-_ ]+(\d+)/i);
+  if (fableMatch) {
+    return `claude-fable-${fableMatch[1]}`;
+  }
+
   // Match: claude-{family}-{major}-{minor}[1m]? possibly followed by a date suffix
   const runtimeMatch = trimmed.match(
     /(?:claude-)?(opus|sonnet|haiku)[-_ ]+(\d+)[-.](\d+)(\[1m\])?/i,