feat(providers): add OpenRouter and OpenCode support

AGENTS.md

@@ -107,7 +107,7 @@ MetaAgent (optimizer loop)
 | `HarnessSpec.ts`         | Optimizer state, harness manifest, diagnosis output |
 | `MetaAgent.ts`           | Meta-agent optimizer (assisted + autonomous modes)  |
 | `Metrics.ts`             | Token/cost metrics extraction + trajectory JSON     |
-| `Providers.ts`           | OpenAI + Anthropic LanguageModel layers             |
+| `Providers.ts`           | OpenAI-compatible LanguageModel layers              |
 | `ShellTool.ts`           | Low-level shell execution effect                    |
 | `TaskSpec.ts`            | Task directory reader with TOML parsing             |
 | `TrajectoryConverter.ts` | OpenAI/Claude SDK messages → ATIF conversion        |
@@ -164,10 +164,15 @@ All errors extend `Schema.TaggedErrorClass` and are recoverable via
 ```ts
 openAiModel('gpt-5.4'); // Layer<LanguageModel, never, never>
 anthropicModel('claude-sonnet-4-6'); // Layer<LanguageModel, never, never>
+openRouterModel('openai/gpt-4o'); // OpenAI-compatible Chat Completions
+openCodeModel('kimi-k2.5'); // OpenCode Zen
+openCodeGoModel('kimi-k3'); // OpenCode Go
 ```
 
-Both are fully wired (include HttpClient + API key config). Pass directly
-to `AgentExecutor.layer` via `Layer.provide`.
+All bundled layers include the HTTP client and API key config. OpenRouter,
+OpenCode Zen, and OpenCode Go use their documented OpenAI-compatible endpoints;
+pass `protocol: 'responses'` to an OpenCode helper for a Responses model. Pass
+the selected layer directly to `AgentExecutor.layer` via `Layer.provide`.
 
 ## CLI Usage
 

README.md

@@ -53,7 +53,7 @@ tools, orchestration strategy, and constraints.
 ## Quick start
 
 **Requirements:** [Bun](https://bun.sh), Docker, and API credentials for your
-chosen provider (OpenAI or Anthropic).
+chosen provider (OpenAI, Anthropic, OpenRouter, or OpenCode).
 
 ```bash
 # 1. Install dependencies
@@ -62,6 +62,10 @@ bun install
 # 2. Set up environment variables
 cat > .env << 'EOF'
 OPENAI_API_KEY=...
+# Use the key matching the selected compatible provider.
+OPENROUTER_API_KEY=...
+OPENCODE_API_KEY=...
+OPENCODE_GO_API_KEY=...
 EOF
 
 # 3. Verify the harness compiles
@@ -131,7 +135,7 @@ src/
   HarnessSpec.ts             — optimizer state, harness manifest, diagnosis output
   MetaAgent.ts               — meta-agent optimizer (assisted + autonomous modes)
   Metrics.ts                 — token/cost metrics + trajectory JSON serialization
-  Providers.ts               — OpenAI + Anthropic LanguageModel layers
+  Providers.ts               — OpenAI-compatible LanguageModel layers
   ShellTool.ts               — low-level shell execution effect
   TaskSpec.ts                — task directory reader with TOML parsing
   TrajectoryConverter.ts     — OpenAI/Claude SDK messages → ATIF conversion
@@ -202,7 +206,8 @@ MetaAgent (optimizer loop)
 
 ## Providers
 
-Both OpenAI and Anthropic are supported as fully-wired `LanguageModel` layers:
+OpenAI, Anthropic, OpenRouter, and OpenCode are supported as fully-wired
+`LanguageModel` layers:
 
 ```ts
 import { openAiModel, anthropicModel } from 'effect-autoagent';
@@ -211,7 +216,26 @@ openAiModel('gpt-5.4'); // Layer<LanguageModel>
 anthropicModel('claude-sonnet-4-6'); // Layer<LanguageModel>
 ```
 
-API keys are read from config (`OPENAI_API_KEY` / `ANTHROPIC_API_KEY`).
+OpenAI-compatible providers use the published Chat Completions package:
+
+```ts
+import {
+	openCodeGoModel,
+	openCodeModel,
+	openRouterModel
+} from 'effect-autoagent';
+
+openRouterModel('openai/gpt-4o'); // OPENROUTER_API_KEY
+openCodeModel('kimi-k2.5'); // OPENCODE_API_KEY (Zen)
+openCodeGoModel('kimi-k3'); // OPENCODE_GO_API_KEY (or OPENCODE_API_KEY)
+openCodeModel('gpt-5.4', { protocol: 'responses' });
+```
+
+API keys are read from config (`OPENAI_API_KEY`, `ANTHROPIC_API_KEY`,
+`OPENROUTER_API_KEY`, `OPENCODE_API_KEY`, and `OPENCODE_GO_API_KEY`). Endpoint
+defaults can be overridden with `OPENROUTER_API_URL`, `OPENCODE_API_URL`, and
+`OPENCODE_GO_API_URL`. The CLI accepts `--provider openrouter`,
+`--provider opencode`, and `--provider opencode-go`.
 
 ## Library usage
 

package.json

@@ -50,6 +50,7 @@
   "dependencies": {
     "@effect/ai-anthropic": "4.0.0-beta.46",
     "@effect/ai-openai": "4.0.0-beta.46",
+    "@effect/ai-openai-compat": "4.0.0-beta.46",
     "@effect/platform-bun": "4.0.0-beta.46",
     "smol-toml": "^1.6.1"
   },

src/AgentBlueprint.ts

@@ -27,7 +27,13 @@ import { defaultToolSpecs, ToolSpec } from './ToolSpec.js';
  *
  * @since 0.3.0
  */
-export const ModelProvider = Schema.Literals(['openai', 'anthropic']).annotate({
+export const ModelProvider = Schema.Literals([
+	'openai',
+	'anthropic',
+	'openrouter',
+	'opencode',
+	'opencode-go'
+]).annotate({
 	title: 'ModelProvider',
 	description: 'LLM provider for the agent.'
 });

src/AgentFactory.ts

@@ -16,7 +16,7 @@ import * as Str from 'effect/String';
 import { Chat, LanguageModel, Prompt } from 'effect/unstable/ai';
 import type * as Tool from 'effect/unstable/ai/Tool';
 
-import { type AgentBlueprint } from './AgentBlueprint.js';
+import { type AgentBlueprint, type ModelProvider } from './AgentBlueprint.js';
 import { AgentRunResult, type ExitReason } from './AgentRunResult.js';
 import { AgentInfo, AtifStep, buildTrajectory, FinalMetrics } from './Atif.js';
 import {
@@ -31,7 +31,13 @@ import type {
 	PlanAndExecute,
 	WithVerifier
 } from './OrchestrationSpec.js';
-import { anthropicModel, openAiModel } from './Providers.js';
+import {
+	anthropicModel,
+	openAiModel,
+	openCodeGoModel,
+	openCodeModel,
+	openRouterModel
+} from './Providers.js';
 import { ToolFactory, type BuiltToolkit } from './ToolFactory.js';
 import { UsageSnapshot } from './UsageMetrics.js';
 
@@ -883,16 +889,32 @@ const runWithVerifier = Effect.fn('AgentFactory.withVerifier')(function* (
  * Infer the provider from a model name using prefix heuristics.
  *
  * - `claude-*` → Anthropic
+ * - `openrouter/*` → OpenRouter
+ * - `opencode/*` → OpenCode Zen
+ * - `opencode-go/*` → OpenCode Go
  * - Everything else → OpenAI (safest fallback for unknown models)
  *
  * @internal
  */
-const inferProvider = (modelName: string): 'openai' | 'anthropic' =>
+const inferProvider = (modelName: string): ModelProvider =>
 	Match.value(modelName).pipe(
 		Match.when(Str.startsWith('claude'), () => 'anthropic' as const),
+		Match.when(Str.startsWith('openrouter/'), () => 'openrouter' as const),
+		Match.when(
+			Str.startsWith('opencode-go/'),
+			() => 'opencode-go' as const
+		),
+		Match.when(Str.startsWith('opencode/'), () => 'opencode' as const),
 		Match.orElse(() => 'openai' as const)
 	);
 
+const stripProviderPrefix = (modelName: string, provider: ModelProvider) => {
+	const prefix = `${provider}/`;
+	return modelName.startsWith(prefix)
+		? modelName.slice(prefix.length)
+		: modelName;
+};
+
 /**
  * Model fallback strategy.
  *
@@ -927,11 +949,18 @@ const runFallbackModels = Effect.fn('AgentFactory.fallbackModels')(function* (
 			);
 
 			const provider = inferProvider(modelName);
+			const providerModel = stripProviderPrefix(modelName, provider);
 			// ConfigError from API key lookup is unrecoverable — orDie per EF-31
 			const modelLayer = Layer.orDie(
 				provider === 'openai'
-					? openAiModel(modelName)
-					: anthropicModel(modelName)
+					? openAiModel(providerModel)
+					: provider === 'anthropic'
+						? anthropicModel(providerModel)
+						: provider === 'openrouter'
+							? openRouterModel(providerModel)
+							: provider === 'opencode'
+								? openCodeModel(providerModel)
+								: openCodeGoModel(providerModel)
 			);
 
 			const loopLayer = Layer.mergeAll(modelLayer, envLayer).pipe(