feat: add models.dev-backed model capabilities

src/shared/model-capabilities.test.ts

@@ -0,0 +1,159 @@
+import { describe, expect, test } from "bun:test"
+
+import {
+  getModelCapabilities,
+  type ModelCapabilitiesSnapshot,
+} from "./model-capabilities"
+
+describe("getModelCapabilities", () => {
+  const bundledSnapshot: ModelCapabilitiesSnapshot = {
+    generatedAt: "2026-03-25T00:00:00.000Z",
+    sourceUrl: "https://models.dev/api.json",
+    models: {
+      "claude-opus-4-6": {
+        id: "claude-opus-4-6",
+        family: "claude-opus",
+        reasoning: true,
+        temperature: true,
+        modalities: {
+          input: ["text", "image", "pdf"],
+          output: ["text"],
+        },
+        limit: {
+          context: 1_000_000,
+          output: 128_000,
+        },
+        toolCall: true,
+      },
+      "gemini-3.1-pro-preview": {
+        id: "gemini-3.1-pro-preview",
+        family: "gemini",
+        reasoning: true,
+        temperature: true,
+        modalities: {
+          input: ["text", "image"],
+          output: ["text"],
+        },
+        limit: {
+          context: 1_000_000,
+          output: 65_000,
+        },
+      },
+      "gpt-5.4": {
+        id: "gpt-5.4",
+        family: "gpt",
+        reasoning: true,
+        temperature: false,
+        modalities: {
+          input: ["text", "image", "pdf"],
+          output: ["text"],
+        },
+        limit: {
+          context: 1_050_000,
+          output: 128_000,
+        },
+      },
+    },
+  }
+
+  test("uses runtime metadata before snapshot data", () => {
+    const result = getModelCapabilities({
+      providerID: "anthropic",
+      modelID: "claude-opus-4-6",
+      runtimeModel: {
+        variants: {
+          low: {},
+          medium: {},
+          high: {},
+        },
+      },
+      bundledSnapshot,
+    })
+
+    expect(result).toMatchObject({
+      canonicalModelID: "claude-opus-4-6",
+      family: "claude-opus",
+      variants: ["low", "medium", "high"],
+      supportsThinking: true,
+      supportsTemperature: true,
+      maxOutputTokens: 128_000,
+      toolCall: true,
+    })
+  })
+
+  test("normalizes thinking suffix aliases before snapshot lookup", () => {
+    const result = getModelCapabilities({
+      providerID: "anthropic",
+      modelID: "claude-opus-4-6-thinking",
+      bundledSnapshot,
+    })
+
+    expect(result).toMatchObject({
+      canonicalModelID: "claude-opus-4-6",
+      family: "claude-opus",
+      supportsThinking: true,
+      supportsTemperature: true,
+      maxOutputTokens: 128_000,
+    })
+  })
+
+  test("maps local gemini aliases to canonical models.dev entries", () => {
+    const result = getModelCapabilities({
+      providerID: "google",
+      modelID: "gemini-3.1-pro-high",
+      bundledSnapshot,
+    })
+
+    expect(result).toMatchObject({
+      canonicalModelID: "gemini-3.1-pro-preview",
+      family: "gemini",
+      supportsThinking: true,
+      supportsTemperature: true,
+      maxOutputTokens: 65_000,
+    })
+  })
+
+  test("prefers runtime models.dev cache over bundled snapshot", () => {
+    const runtimeSnapshot: ModelCapabilitiesSnapshot = {
+      ...bundledSnapshot,
+      models: {
+        ...bundledSnapshot.models,
+        "gpt-5.4": {
+          ...bundledSnapshot.models["gpt-5.4"],
+          limit: {
+            context: 1_050_000,
+            output: 64_000,
+          },
+        },
+      },
+    }
+
+    const result = getModelCapabilities({
+      providerID: "openai",
+      modelID: "gpt-5.4",
+      bundledSnapshot,
+      runtimeSnapshot,
+    })
+
+    expect(result).toMatchObject({
+      canonicalModelID: "gpt-5.4",
+      maxOutputTokens: 64_000,
+      supportsTemperature: false,
+    })
+  })
+
+  test("falls back to heuristic family rules when no snapshot entry exists", () => {
+    const result = getModelCapabilities({
+      providerID: "openai",
+      modelID: "o3-mini",
+      bundledSnapshot,
+    })
+
+    expect(result).toMatchObject({
+      canonicalModelID: "o3-mini",
+      family: "openai-reasoning",
+      variants: ["low", "medium", "high"],
+      reasoningEfforts: ["none", "minimal", "low", "medium", "high"],
+    })
+  })
+})