feat: add Fable using host-owned model routing

README.md

@@ -122,12 +122,13 @@ $cc:review --base main              # review branch vs main
 $cc:review --scope branch           # explicitly compare branch tip to base
 $cc:review --background             # run in background, check with $cc:status later
 $cc:review --model sonnet           # switch to sonnet (defaults to high effort)
+$cc:review --model fable            # use Fable (defaults to high effort)
 $cc:review --model opus --effort high   # opus with a lighter effort
 ```
 
-**Flags:** `--base <ref>`, `--scope <auto|working-tree|branch>`, `--wait`, `--background`, `--model <model>`, `--effort <low|medium|high|max>`
+**Flags:** `--base <ref>`, `--scope <auto|working-tree|branch>`, `--wait`, `--background`, `--model <model>`, `--effort <low|medium|high|xhigh|max>`
 
-**Defaults:** model `opus` (resolves to `claude-opus-4-7[1m]`, the 1M-context variant) with `xhigh` effort. If you pick `sonnet`, it resolves to `claude-sonnet-4-6[1m]` (also 1M context) and the default effort drops to `high`. `haiku` resolves to `claude-haiku-4-5` and has no effort setting. Pass `--model` and `--effort` to override.
+**Defaults:** model `opus` (resolves to `claude-opus-4-7[1m]`, the 1M-context variant) with `xhigh` effort. If you pick `sonnet`, it resolves to `claude-sonnet-4-6[1m]` (also 1M context) and the default effort drops to `high`. `fable` passes through to Claude Code and also defaults to `high`. `haiku` resolves to `claude-haiku-4-5` and has no effort setting. Pass `--model` and `--effort` to override.
 
 Scope `auto` (the default) inspects `git status` and chooses between working-tree and branch automatically.
 
@@ -171,8 +172,8 @@ $cc:rescue --model sonnet --effort medium investigate the flaky test
 | `--resume-last` | Alias for `--resume` |
 | `--fresh` | Force a new task (don't resume) |
 | `--write` | Allow file edits (default) |
-| `--model <model>` | Claude model (`opus`, `sonnet`, `haiku`, or full ID; defaults to `opus`. The `opus` and `sonnet` aliases resolve to their 1M-context variants `claude-opus-4-7[1m]` and `claude-sonnet-4-6[1m]`.) |
-| `--effort <level>` | Reasoning effort: `low`, `medium`, `high`, `xhigh`, `max` (default: `xhigh` for opus, `high` for sonnet, unset for haiku) |
+| `--model <model>` | Claude model (`fable`, `opus`, `sonnet`, `haiku`, or full ID; defaults to `opus`. `fable` passes through to Claude Code. The `opus` and `sonnet` aliases resolve to their 1M-context variants `claude-opus-4-7[1m]` and `claude-sonnet-4-6[1m]`.) |
+| `--effort <level>` | Reasoning effort: `low`, `medium`, `high`, `xhigh`, `max` (default: `xhigh` for opus, `high` for sonnet and fable, unset for haiku) |
 | `--prompt-file <path>` | Read task description from a file |
 
 **Resume behavior:** If you don't pass `--resume` or `--fresh`, rescue checks for a resumable Claude session and asks once whether to continue or start fresh. Your phrasing guides the recommendation — "continue the last run" → resume, "start over" → fresh.
@@ -278,7 +279,7 @@ The review gate is an **optional turn-end hook**. When enabled, Codex runs a Cla
 | **Runtime** | Codex app-server + broker | Fresh `claude -p` subprocess per invocation |
 | **Review gate trigger** | End of Claude Code turn | End of Codex turn |
 | **Review gate target** | Reviews previous Claude response | Reviews previous Codex response |
-| **Model flags** | Codex model names and effort controls | Claude model names and effort values (`low` / `medium` / `high` / `max`) |
+| **Model flags** | Codex model names and effort controls | Claude model names and effort values (`low` / `medium` / `high` / `xhigh` / `max`) |
 
 ### Where This Goes Further
 

internal-skills/cli-runtime/runtime.md

@@ -24,7 +24,7 @@ Command selection:
 
 Routing controls:
 - Treat `--model`, `--effort`, `--resume`, `--resume-last`, `--fresh`, `--prompt-file`, `--view-state`, `--owner-session-id`, and `--job-id` as routing controls, not task text.
-- Leave `--model` and `--effort` unset unless the user explicitly asks for a specific model or effort. The companion command applies these defaults itself: model defaults to `opus`, effort defaults to `xhigh` for opus, `high` for sonnet, and is left unset for haiku.
+- Leave `--model` and `--effort` unset unless the user explicitly asks for a specific model or effort. The companion command applies these defaults itself: model defaults to `opus`, effort defaults to `xhigh` for opus, `high` for sonnet and fable, and is left unset for haiku.
 - `--view-state on-success` means the user will see this companion result in the current turn, so the companion may mark it viewed on success.
 - `--view-state defer` means the parent is not waiting, so the companion must leave the result unread until the user explicitly checks it.
 - `--owner-session-id <session-id>` is an internal parent-session routing control. Preserve it when present so tracked jobs remain visible to the parent session's `$cc:status` / `$cc:result`.

scripts/claude-companion.mjs

@@ -12,7 +12,7 @@
  * - Uses claude-cli.mjs instead of app-server/broker
  * - MODEL_ALIASES: opus -> claude-opus-4-7[1m], sonnet -> claude-sonnet-4-6[1m], haiku -> claude-haiku-4-5
  * - Default model when --model is unset: opus
- * - Default effort by model: opus -> xhigh, sonnet -> high, haiku -> unset
+ * - Default effort by model: opus -> xhigh, sonnet|fable -> high, haiku -> unset
  * - Claude CLI effort values: low, medium, high, xhigh, max
  * - Legacy effort aliases: none|minimal -> low
  * - Review gate matches upstream setup semantics: Stop hook runs when enabled
@@ -137,9 +137,9 @@ function printUsage() {
     [
       "Usage:",
       "  node scripts/claude-companion.mjs setup [--enable-review-gate|--disable-review-gate] [--json]",
-      "  node scripts/claude-companion.mjs review [--wait|--background] [--base <ref>] [--scope <auto|working-tree|branch>] [--model <model|opus|sonnet|haiku>] [--effort <low|medium|high|xhigh|max>]",
-      "  node scripts/claude-companion.mjs adversarial-review [--wait|--background] [--base <ref>] [--scope <auto|working-tree|branch>] [--model <model|opus|sonnet|haiku>] [--effort <low|medium|high|xhigh|max>] [focus text]",
-      "  node scripts/claude-companion.mjs task [--background] [--write] [--resume-last|--resume|--fresh] [--model <model|opus|sonnet|haiku>] [--effort <low|medium|high|xhigh|max>] [prompt]",
+      "  node scripts/claude-companion.mjs review [--wait|--background] [--base <ref>] [--scope <auto|working-tree|branch>] [--model <model|fable|opus|sonnet|haiku>] [--effort <low|medium|high|xhigh|max>]",
+      "  node scripts/claude-companion.mjs adversarial-review [--wait|--background] [--base <ref>] [--scope <auto|working-tree|branch>] [--model <model|fable|opus|sonnet|haiku>] [--effort <low|medium|high|xhigh|max>] [focus text]",
+      "  node scripts/claude-companion.mjs task [--background] [--write] [--resume-last|--resume|--fresh] [--model <model|fable|opus|sonnet|haiku>] [--effort <low|medium|high|xhigh|max>] [prompt]",
       "  node scripts/claude-companion.mjs status [job-id] [--all] [--json]",
       "  node scripts/claude-companion.mjs result [job-id] [--json]",
       "  node scripts/claude-companion.mjs cancel [job-id] [--json]",

scripts/lib/claude-cli.mjs

@@ -659,6 +659,7 @@ export const DEFAULT_EFFORT_BY_MODEL = new Map([
   ["sonnet", "high"],
   ["claude-sonnet-4-6", "high"],
   ["claude-sonnet-4-6[1m]", "high"],
+  ["fable", "high"],
 ]);
 
 export function resolveDefaultModel(model) {

skills/adversarial-review/SKILL.md

@@ -16,7 +16,7 @@ Unlike `$cc:review`, this skill accepts custom focus text after the flags. The m
 Resolve `<plugin-root>` as two directories above this `SKILL.md` file. Always run the companion from that active plugin root:
 `node "<plugin-root>/scripts/claude-companion.mjs" adversarial-review ...`
 
-Supported arguments: `--wait`, `--background`, `--base <ref>`, `--scope auto|working-tree|branch`, `--model <model>`, `--effort <low|medium|high|xhigh|max>`, plus optional focus text after the flags (defaults: model=opus, effort=xhigh; sonnet defaults to high; haiku has no effort)
+Supported arguments: `--wait`, `--background`, `--base <ref>`, `--scope auto|working-tree|branch`, `--model <model>`, `--effort <low|medium|high|xhigh|max>`, plus optional focus text after the flags (defaults: model=opus, effort=xhigh; sonnet and fable default to high; haiku has no effort)
 
 Raw slash-command arguments:
 `$ARGUMENTS`

skills/rescue/SKILL.md

@@ -24,6 +24,8 @@ Raw slash-command arguments:
 
 Supported arguments: `--background`, `--wait`, `--resume`, `--resume-last`, `--fresh`, `--write`, `--model <model>`, `--effort <low|medium|high|xhigh|max>`, `--prompt-file <path>`, plus free-text task text
 
+Companion defaults: model=opus, effort=xhigh; sonnet and fable default to high; haiku has no effort.
+
 Main-thread routing rules:
 - If the user explicitly invoked `$cc:rescue` or `Claude Code Rescue`, do not keep the work in the main Codex thread. Delegate it.
 - If the user did not supply a task, ask what Claude Code should investigate or fix.

skills/review/SKILL.md

@@ -16,7 +16,7 @@ If the overall request is "you review it too, also ask Claude to review in the b
 Resolve `<plugin-root>` as two directories above this `SKILL.md` file. Always run the companion from that active plugin root:
 `node "<plugin-root>/scripts/claude-companion.mjs" review ...`
 
-Supported arguments: `--wait`, `--background`, `--base <ref>`, `--scope auto|working-tree|branch`, `--model <model>`, `--effort <low|medium|high|xhigh|max>` (defaults: model=opus, effort=xhigh; sonnet defaults to high; haiku has no effort)
+Supported arguments: `--wait`, `--background`, `--base <ref>`, `--scope auto|working-tree|branch`, `--model <model>`, `--effort <low|medium|high|xhigh|max>` (defaults: model=opus, effort=xhigh; sonnet and fable default to high; haiku has no effort)
 
 Raw slash-command arguments:
 `$ARGUMENTS`

tests/claude-cli.test.mjs

@@ -440,6 +440,10 @@ describe("resolveModel", () => {
     assert.equal(resolveModel("claude-3-opus-20240229"), "claude-3-opus-20240229");
   });
 
+  it("passes the native 'fable' alias through unchanged", () => {
+    assert.equal(resolveModel("fable"), "fable");
+  });
+
   it("returns undefined for null/undefined input", () => {
     assert.equal(resolveModel(null), undefined);
     assert.equal(resolveModel(undefined), undefined);
@@ -458,6 +462,7 @@ describe("resolveModel", () => {
     assert.ok(MODEL_ALIASES.has("opus"));
     assert.ok(MODEL_ALIASES.has("sonnet"));
     assert.ok(MODEL_ALIASES.has("haiku"));
+    assert.equal(MODEL_ALIASES.has("fable"), false);
   });
 });
 
@@ -475,6 +480,7 @@ describe("resolveDefaultModel", () => {
 
   it("passes through an explicit model", () => {
     assert.equal(resolveDefaultModel("sonnet"), "sonnet");
+    assert.equal(resolveDefaultModel("fable"), "fable");
     assert.equal(resolveDefaultModel("haiku"), "haiku");
     assert.equal(resolveDefaultModel("claude-opus-4-7"), "claude-opus-4-7");
   });
@@ -498,6 +504,11 @@ describe("resolveDefaultEffort", () => {
     assert.equal(resolveDefaultEffort("claude-sonnet-4-6[1m]", null), "high");
   });
 
+  it("defaults to high for the native fable alias", () => {
+    assert.equal(resolveDefaultEffort("fable", null), "high");
+    assert.equal(resolveDefaultEffort("FABLE", undefined), "high");
+  });
+
   it("returns undefined for haiku (no effort default)", () => {
     assert.equal(resolveDefaultEffort("haiku", null), undefined);
     assert.equal(resolveDefaultEffort("claude-haiku-4-5", undefined), undefined);
@@ -526,6 +537,7 @@ describe("resolveDefaultEffort", () => {
     assert.equal(DEFAULT_EFFORT_BY_MODEL.get("sonnet"), "high");
     assert.equal(DEFAULT_EFFORT_BY_MODEL.get("claude-sonnet-4-6"), "high");
     assert.equal(DEFAULT_EFFORT_BY_MODEL.get("claude-sonnet-4-6[1m]"), "high");
+    assert.equal(DEFAULT_EFFORT_BY_MODEL.get("fable"), "high");
     assert.equal(DEFAULT_EFFORT_BY_MODEL.has("haiku"), false);
   });
 });
@@ -735,6 +747,13 @@ describe("buildArgs", () => {
     assert.equal(args[idx + 1], "claude-sonnet-4-6[1m]");
   });
 
+  it("includes the native fable alias unchanged", () => {
+    const args = buildArgs("p", { model: "fable" });
+    const idx = args.indexOf("--model");
+    assert.ok(idx >= 0);
+    assert.equal(args[idx + 1], "fable");
+  });
+
   it("includes --effort with resolved effort", () => {
     const args = buildArgs("p", { effort: "xhigh" });
     const idx = args.indexOf("--effort");

tests/integration/claude-companion.test.mjs

@@ -954,6 +954,69 @@ describe("claude-companion integration", () => {
     }
   });
 
+  it("passes native Fable with high default effort through task and review flows", () => {
+    const testEnv = createTestEnvironment();
+
+    try {
+      const taskArgsFile = path.join(testEnv.rootDir, "fable-task-args.json");
+      runCompanion(
+        [
+          "task",
+          "--cwd",
+          testEnv.workspaceDir,
+          "--model",
+          "fable",
+          "--quiet-progress",
+          "fable task delay=20",
+        ],
+        {
+          env: {
+            ...testEnv.env,
+            CLAUDE_ARGS_FILE: taskArgsFile,
+          },
+        }
+      );
+
+      const taskArgs = JSON.parse(fs.readFileSync(taskArgsFile, "utf8"));
+      assert.equal(taskArgs[taskArgs.indexOf("--model") + 1], "fable");
+      assert.equal(taskArgs[taskArgs.indexOf("--effort") + 1], "high");
+
+      setupGitWorkspace(testEnv.workspaceDir);
+      seedWorkingTreeDiff(testEnv.workspaceDir);
+
+      for (const [command, focusText] of [
+        ["review", []],
+        ["adversarial-review", ["focus on model routing"]],
+      ]) {
+        const invocationFile = path.join(testEnv.rootDir, `fable-${command}-invocation.json`);
+        runCompanion(
+          [
+            command,
+            "--cwd",
+            testEnv.workspaceDir,
+            "--scope",
+            "working-tree",
+            "--model",
+            "fable",
+            ...focusText,
+          ],
+          {
+            env: {
+              ...testEnv.env,
+              CLAUDE_INVOCATION_FILE: invocationFile,
+            },
+          }
+        );
+
+        const invocation = JSON.parse(fs.readFileSync(invocationFile, "utf8"));
+        assert.equal(invocation.args[invocation.args.indexOf("--model") + 1], "fable");
+        assert.equal(invocation.args[invocation.args.indexOf("--effort") + 1], "high");
+      }
+    } finally {
+      cleanupTestEnvironment(testEnv);
+    }
+  });
+
   it("uses --resume to continue the latest session and keeps --fresh from injecting a resume id", async () => {
     const testEnv = createTestEnvironment();
     const sessionEnv = {

tests/skills-contracts.test.mjs

@@ -16,6 +16,22 @@ function read(relativePath) {
   return fs.readFileSync(path.join(PROJECT_ROOT, relativePath), "utf8");
 }
 
+test("public model contracts document native Fable support", () => {
+  const contracts = [
+    "README.md",
+    "skills/review/SKILL.md",
+    "skills/adversarial-review/SKILL.md",
+    "skills/rescue/SKILL.md",
+    "internal-skills/cli-runtime/runtime.md",
+  ];
+
+  for (const contractPath of contracts) {
+    const contract = read(contractPath);
+    assert.match(contract, /fable/i, `${contractPath} must document Fable`);
+    assert.match(contract, /fable[^\n]*high|high[^\n]*fable/i, `${contractPath} must document Fable's high default effort`);
+  }
+});
+
 test("built-in child commands preserve the workspace for reserved job ids", () => {
   const skills = [
     ["rescue", "skills/rescue/SKILL.md"],