feat(caps): Fable 5 / 5.1 carry their 1M window under every id they arrive as

Fable reaches the composer two ways — through the gateway as the OpenRouter basename
(dotted `claude-fable-5.1`) and BYOK-native as the dashed `claude-fable-5-1` — and neither
had a row, so both fell to the claude-* heuristic's 200k: a fifth of the real window, and
the meter sized every Fable conversation against it. Vision was already right by luck of the
heuristic; the window was not.

Three explicit rows, one per spelling. Matters more now that Fable 5 / 5.1 are Pro-tier on
the gateway (thin.ly, 2026-09-08) rather than Max-only.

Verified: catalog 15 tests (was 14); imageCost 9, imageAttach 30. Rows reverted -> the new
test fails.

Author: ndemianc

extensions/levelcode-ai/providers/catalog.js

@@ -29,6 +29,12 @@ const CAPS = {
 	'claude-opus-4-8':           { context: 200000, tools: true, vision: true, caching: true },
 	'claude-sonnet-4-6':         { context: 200000, tools: true, vision: true, caching: true },
 	'claude-haiku-4-5-20251001': { context: 200000, tools: true, vision: true, fast: true },
+	// Fable reaches the composer two ways: through the gateway as the OpenRouter basename (dotted
+	// 5.1), and BYOK-native as the dashed id. Neither had a row, so both fell to the claude-*
+	// heuristic's 200k — a fifth of the real window. Fable 5 / 5.1 are Pro-tier from 2026-09-08.
+	'claude-fable-5':   { context: 1000000, tools: true, vision: true, caching: true },
+	'claude-fable-5.1': { context: 1000000, tools: true, vision: true, caching: true },
+	'claude-fable-5-1': { context: 1000000, tools: true, vision: true, caching: true },
 	// OpenAI
 	'gpt-4o':      { context: 128000, tools: true, vision: true },
 	'gpt-4o-mini': { context: 128000, tools: true, vision: true, fast: true },

extensions/levelcode-ai/test/catalog.test.js

@@ -27,6 +27,12 @@ test('modelCaps: gpt-6-astra is an explicit row, not the gpt-4/5 heuristic', ()
 	assert.strictEqual(C.supportsVisionForModel('openai', 'gpt-6-astra'), true);
 	assert.strictEqual(C.contextWindowFor('openai', 'gpt-6-astra'), 1050000);
 });
+test('modelCaps: Fable 5 / 5.1 carry the 1M window under every id they arrive as', () => {
+	for (const id of ['anthropic/claude-fable-5', 'anthropic/claude-fable-5.1', 'claude-fable-5-1']) {
+		assert.deepStrictEqual(C.modelCaps(id), { context: 1000000, tools: true, vision: true, caching: true }, id);
+		assert.strictEqual(C.contextWindowFor('openai', id), 1000000, id);
+	}
+});
 test('modelCaps: family heuristics for unknown ids', () => {
 	assert.strictEqual(C.modelCaps('o4-mini').reasoning, true);       // o-series
 	assert.strictEqual(C.modelCaps('claude-3-5-haiku-latest').vision, true);