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Add Claude Fable 5 model #3009

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Merged
juliusmarminge merged 6 commits into from
Jun 9, 2026
Merged

Add Claude Fable 5 model #3009

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c8cbc04
feat: add Claude Fable 5 model
juliusmarminge Jun 9, 2026
22af73b
Add Claude Fable 5 provider capabilities
juliusmarminge Jun 9, 2026
648538a
test: avoid coupling Claude model presence to capabilities
juliusmarminge Jun 9, 2026
e8d43cb
feat: gate Claude Fable 5 by CLI version
juliusmarminge Jun 9, 2026
9f57633
fix: preserve xhigh effort for Claude Fable 5
juliusmarminge Jun 9, 2026
cbe8a20
Inline Claude effort options for new models
juliusmarminge Jun 9, 2026
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63 changes: 59 additions & 4 deletions apps/server/src/provider/Layers/ClaudeProvider.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -48,10 +48,20 @@ const CLAUDE_PRESENTATION = {
displayName: "Claude",
showInteractionModeToggle: true,
} as const;
const MINIMUM_CLAUDE_FABLE_5_VERSION = "2.1.169";
const MINIMUM_CLAUDE_OPUS_4_8_VERSION = "2.1.154";
const MINIMUM_CLAUDE_OPUS_4_7_VERSION = "2.1.111";

const CLAUDE_EFFORT_OPTIONS = {
fable48: [

@buzinas buzinas Jun 9, 2026

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Shouldn't this be fable5 (or maybe fable50)?

{ value: "low", label: "Low" },
{ value: "medium", label: "Medium" },
{ value: "high", label: "High", isDefault: true },
{ value: "xhigh", label: "Extra High" },
{ value: "max", label: "Max" },
{ value: "ultracode", label: "Ultracode" },
{ value: "ultrathink", label: "Ultrathink" },
],
opus48: [
{ value: "low", label: "Low" },
{ value: "medium", label: "Medium" },
Expand Down Expand Up @@ -92,6 +102,29 @@ const CLAUDE_EFFORT_OPTIONS = {
} as const;

const BUILT_IN_MODELS: ReadonlyArray<ServerProviderModel> = [
{
slug: "claude-fable-5",
name: "Claude Fable 5",
isCustom: false,
capabilities: createModelCapabilities({
optionDescriptors: [
buildSelectOptionDescriptor({
id: "effort",
label: "Reasoning",
options: CLAUDE_EFFORT_OPTIONS.fable48,
promptInjectedValues: ["ultrathink"],
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}),
buildSelectOptionDescriptor({
id: "contextWindow",
label: "Context Window",
options: [
{ value: "200k", label: "200k", isDefault: true },
{ value: "1m", label: "1M" },
],
}),
],
}),
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},
{
slug: "claude-opus-4-8",
name: "Claude Opus 4.8",
Expand All @@ -104,6 +137,10 @@ const BUILT_IN_MODELS: ReadonlyArray<ServerProviderModel> = [
options: CLAUDE_EFFORT_OPTIONS.opus48,
promptInjectedValues: ["ultrathink"],
}),
buildBooleanOptionDescriptor({
id: "fastMode",
label: "Fast Mode",
}),
buildSelectOptionDescriptor({
id: "contextWindow",
label: "Context Window",
Expand All @@ -127,6 +164,10 @@ const BUILT_IN_MODELS: ReadonlyArray<ServerProviderModel> = [
options: CLAUDE_EFFORT_OPTIONS.opus47,
promptInjectedValues: ["ultrathink"],
}),
buildBooleanOptionDescriptor({
id: "fastMode",
label: "Fast Mode",
}),
buildSelectOptionDescriptor({
id: "contextWindow",
label: "Context Window",
Expand Down Expand Up @@ -221,6 +262,10 @@ const BUILT_IN_MODELS: ReadonlyArray<ServerProviderModel> = [
},
];

function supportsClaudeFable5(version: string | null | undefined): boolean {
return version ? compareSemverVersions(version, MINIMUM_CLAUDE_FABLE_5_VERSION) >= 0 : false;
}

function supportsClaudeOpus48(version: string | null | undefined): boolean {
return version ? compareSemverVersions(version, MINIMUM_CLAUDE_OPUS_4_8_VERSION) >= 0 : false;
}
Expand All @@ -233,6 +278,9 @@ function getBuiltInClaudeModelsForVersion(
version: string | null | undefined,
): ReadonlyArray<ServerProviderModel> {
return BUILT_IN_MODELS.filter((model) => {
if (model.slug === "claude-fable-5") {
return supportsClaudeFable5(version);
}
if (model.slug === "claude-opus-4-8") {
return supportsClaudeOpus48(version);
}
Expand All @@ -243,6 +291,11 @@ function getBuiltInClaudeModelsForVersion(
});
}

function formatClaudeFable5UpgradeMessage(version: string | null): string {
const versionLabel = version ? `v${version}` : "the installed version";
return `Claude Code ${versionLabel} is too old for Claude Fable 5. Upgrade to v${MINIMUM_CLAUDE_FABLE_5_VERSION} or newer to access it.`;
}

function formatClaudeOpus48UpgradeMessage(version: string | null): string {
const versionLabel = version ? `v${version}` : "the installed version";
return `Claude Code ${versionLabel} is too old for Claude Opus 4.8. Upgrade to v${MINIMUM_CLAUDE_OPUS_4_8_VERSION} or newer to access it.`;
Expand Down Expand Up @@ -688,11 +741,13 @@ export const checkClaudeProviderStatus = Effect.fn("checkClaudeProviderStatus")(
claudeSettings.customModels,
DEFAULT_CLAUDE_MODEL_CAPABILITIES,
);
const versionUpgradeMessage = supportsClaudeOpus48(parsedVersion)
const versionUpgradeMessage = supportsClaudeFable5(parsedVersion)
? undefined
: supportsClaudeOpus47(parsedVersion)
? formatClaudeOpus48UpgradeMessage(parsedVersion)
: formatClaudeOpus47UpgradeMessage(parsedVersion);
: supportsClaudeOpus48(parsedVersion)
? formatClaudeFable5UpgradeMessage(parsedVersion)
: supportsClaudeOpus47(parsedVersion)
? formatClaudeOpus48UpgradeMessage(parsedVersion)
: formatClaudeOpus47UpgradeMessage(parsedVersion);

const capabilities = resolveCapabilities
? yield* resolveCapabilities(claudeSettings).pipe(Effect.orElseSucceed(() => undefined))
Expand Down
56 changes: 56 additions & 0 deletions apps/server/src/provider/Layers/ProviderRegistry.test.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -1367,6 +1367,62 @@ it.layer(Layer.mergeAll(NodeServices.layer, ServerSettingsService.layerTest(), T
),
);

it.effect("includes Claude Fable 5 on supported Claude Code versions", () =>
Effect.gen(function* () {
const status = yield* checkClaudeProviderStatus(
defaultClaudeSettings,
claudeCapabilities(),
);
const fable5 = status.models.find((model) => model.slug === "claude-fable-5");
assert.strictEqual(fable5?.name, "Claude Fable 5");
}).pipe(
Effect.provide(
mockSpawnerLayer((args) => {
const joined = args.join(" ");
if (joined === "--version") return { stdout: "2.1.169\n", stderr: "", code: 0 };
if (joined === "auth status")
return {
stdout: '{"loggedIn":true,"authMethod":"claude.ai"}\n',
stderr: "",
code: 0,
};
throw new Error(`Unexpected args: ${joined}`);
}),
),
),
);

it.effect("hides Claude Fable 5 on older Claude Code versions", () =>
Effect.gen(function* () {
const status = yield* checkClaudeProviderStatus(
defaultClaudeSettings,
claudeCapabilities(),
);
assert.strictEqual(
status.models.some((model) => model.slug === "claude-fable-5"),
false,
);
assert.strictEqual(
status.message,
"Claude Code v2.1.168 is too old for Claude Fable 5. Upgrade to v2.1.169 or newer to access it.",
);
}).pipe(
Effect.provide(
mockSpawnerLayer((args) => {
const joined = args.join(" ");
if (joined === "--version") return { stdout: "2.1.168\n", stderr: "", code: 0 };
if (joined === "auth status")
return {
stdout: '{"loggedIn":true,"authMethod":"claude.ai"}\n',
stderr: "",
code: 0,
};
throw new Error(`Unexpected args: ${joined}`);
}),
),
),
);

it.effect(
"includes Claude Opus 4.7 with xhigh as the default effort on supported versions",
() =>
Expand Down
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