feat(caps): GPT-6 Astra reads images and has a 1.05M window

The gateway picker offers whatever /account/models returns, so a model can reach the
composer before the caps table has heard of it. gpt-6-astra fell through to the default
row: vision false, context 200k. In gateway mode that meant the composer refused every
attachment for it and the context meter sized it against a window a fifth of the real one.

The gpt-4/gpt-5 heuristic would not have caught it either, and if extended to gpt-6 it
would assert a 128k window — wrong by 8x. An explicit row is the honest fix: 1,050,000
ctx and image input, both from the OpenRouter models API on 2026-09-06.

Verified: catalog 14 tests (was 13); full suite 40 suites, 600 cases, 0 failing. Row
reverted -> the new test fails.

Author: ndemianc

extensions/levelcode-ai/providers/catalog.js

@@ -32,6 +32,10 @@ const CAPS = {
 	// OpenAI
 	'gpt-4o':      { context: 128000, tools: true, vision: true },
 	'gpt-4o-mini': { context: 128000, tools: true, vision: true, fast: true },
+	// Not covered by the gpt-4/gpt-5 heuristic below, which would also give it a 128k window; the
+	// real one is 1.05M (OpenRouter models API, 2026-09-06) and it reads images. Without this row the
+	// gateway picker offers it while the composer refuses attachments and the meter sizes it wrong.
+	'gpt-6-astra': { context: 1050000, tools: true, vision: true },
 	'o3-mini':     { context: 200000, tools: true, reasoning: true },
 	'o1':          { context: 200000, tools: true, reasoning: true },
 	'o1-mini':     { context: 128000, tools: false, reasoning: true },   // o1-mini has no function calling

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

@@ -19,6 +19,14 @@ test('modelCaps: exact table hit', () => {
 test('modelCaps: OpenRouter vendor/model matches on basename', () => {
 	assert.deepStrictEqual(C.modelCaps('openai/gpt-4o'), C.modelCaps('gpt-4o'));
 });
+// GPT-6 Astra is a gateway model; the picker offers whatever /account/models returns, so the caps
+// table must already know it or the composer refuses images and the meter assumes a 200k window.
+test('modelCaps: gpt-6-astra is an explicit row, not the gpt-4/5 heuristic', () => {
+	assert.deepStrictEqual(C.modelCaps('gpt-6-astra'), { context: 1050000, tools: true, vision: true });
+	assert.deepStrictEqual(C.modelCaps('openai/gpt-6-astra'), C.modelCaps('gpt-6-astra'));
+	assert.strictEqual(C.supportsVisionForModel('openai', 'gpt-6-astra'), true);
+	assert.strictEqual(C.contextWindowFor('openai', 'gpt-6-astra'), 1050000);
+});
 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);