fix: accept slashes, tildes, and colons in fallback model IDs

README.md

@@ -77,6 +77,8 @@ Minimal example:
 }
 ```
 
+Model IDs may contain `/`, `~`, and `:` (for example OpenRouter keys such as `openrouter/~deepseek/deepseek-flash-latest`).
+
 Most important knobs:
 
 - `defaults.fallbackOn` - which error categories trigger fallback

src/config/agent-loader.ts

@@ -4,7 +4,7 @@ import { homedir } from "os";
 import { basename, extname, isAbsolute, join, relative, resolve } from "path";
 import type { AgentConfig } from "../types.js";
 
-const MODEL_KEY_RE = /^[a-zA-Z0-9_-]{1,100}\/[a-zA-Z0-9._-]{1,100}$/;
+const MODEL_KEY_RE = /^[a-zA-Z0-9_-]{1,100}\/[a-zA-Z0-9._~\/:-]{1,200}$/;
 
 function isPathInside(baseDir: string, targetPath: string): boolean {
   const rel = relative(baseDir, targetPath);

src/config/schema.ts

@@ -3,7 +3,7 @@ import { isAbsolute, relative, resolve } from "path";
 import { z } from "zod";
 import { DEFAULT_CONFIG } from "./defaults.js";
 
-const MODEL_KEY_RE = /^[a-zA-Z0-9_-]{1,100}\/[a-zA-Z0-9._-]{1,100}$/;
+const MODEL_KEY_RE = /^[a-zA-Z0-9_-]{1,100}\/[a-zA-Z0-9._~\/:-]{1,200}$/;
 const home = resolve(homedir());
 
 function formatPath(path: Array<PropertyKey>): string {

test/agent-loader.test.ts

@@ -142,6 +142,77 @@ fallback:
     ]);
   });
 
+  it("accepts multi-segment, tilde, and colon model IDs from agent files", () => {
+    mkdirSync(agentsDir, { recursive: true });
+    writeFileSync(
+      join(agentsDir, "openrouter.md"),
+      `---
+name: OpenRouterAgent
+fallback:
+  models:
+    - opencode/nemotron-3-ultra-free
+    - openrouter/openrouter/free
+    - openrouter/~deepseek/deepseek-flash-latest
+    - openrouter/anthropic/claude-3.5-sonnet:beta
+---
+`
+    );
+
+    const configs = loadAgentFallbackConfigs(dir, dir);
+    expect(configs["OpenRouterAgent"]).toBeDefined();
+    expect(configs["OpenRouterAgent"].fallbackModels).toEqual([
+      "opencode/nemotron-3-ultra-free",
+      "openrouter/openrouter/free",
+      "openrouter/~deepseek/deepseek-flash-latest",
+      "openrouter/anthropic/claude-3.5-sonnet:beta",
+    ]);
+  });
+
+  it("skips malformed keys but keeps OpenRouter-style entries", () => {
+    mkdirSync(agentsDir, { recursive: true });
+    writeFileSync(
+      join(agentsDir, "malformed.md"),
+      `---
+name: MalformedAgent
+fallback:
+  models:
+    - ""
+    - opencode
+    - opencode/
+    - /model
+    - "opencode/ spaced"
+    - "opencode/ model"
+    - ${"p".repeat(101)}/model
+    - openrouter/~deepseek/deepseek-flash-latest
+---
+`
+    );
+
+    const configs = loadAgentFallbackConfigs(dir, dir);
+    expect(configs["MalformedAgent"]).toBeDefined();
+    expect(configs["MalformedAgent"].fallbackModels).toEqual([
+      "openrouter/~deepseek/deepseek-flash-latest",
+    ]);
+  });
+
+  it("accepts a model ID longer than 100 characters up to 200 from agent files", () => {
+    mkdirSync(agentsDir, { recursive: true });
+    const key = `opencode/${"m".repeat(150)}`;
+    writeFileSync(
+      join(agentsDir, "long-id.md"),
+      `---
+name: LongIdAgent
+fallback:
+  models:
+    - ${key}
+---
+`
+    );
+
+    const configs = loadAgentFallbackConfigs(dir, dir);
+    expect(configs["LongIdAgent"].fallbackModels).toEqual([key]);
+  });
+
   it("skips file entirely when all model keys are invalid", () => {
     mkdirSync(agentsDir, { recursive: true });
     writeFileSync(

test/config.test.ts

@@ -27,6 +27,65 @@ describe("parseConfig", () => {
     expect(warnings.length).toBeGreaterThan(0);
   });
 
+  it("accepts multi-segment, tilde, and colon model IDs", () => {
+    const keys = [
+      "opencode/nemotron-3-ultra-free",
+      "openrouter/openrouter/free",
+      "openrouter/~deepseek/deepseek-flash-latest",
+      "openrouter/anthropic/claude-3.5-sonnet:beta",
+    ];
+    const raw = {
+      agents: { "*": { fallbackModels: keys } },
+    };
+    const { config, warnings } = parseConfig(raw);
+    expect(warnings).toHaveLength(0);
+    expect(config.agents?.["*"].fallbackModels).toEqual(keys);
+  });
+
+  it("keeps an OpenRouter-style chain instead of dropping it", () => {
+    const raw = {
+      agents: {
+        build: {
+          fallbackModels: [
+            "openrouter/~deepseek/deepseek-flash-latest",
+            "openrouter/openrouter/free",
+          ],
+        },
+      },
+    };
+    const { config, warnings } = parseConfig(raw);
+    expect(warnings).toHaveLength(0);
+    expect(config.agents?.build.fallbackModels).toEqual([
+      "openrouter/~deepseek/deepseek-flash-latest",
+      "openrouter/openrouter/free",
+    ]);
+  });
+
+  it("rejects malformed model keys", () => {
+    const invalid = [
+      "",
+      "opencode",
+      "opencode/",
+      "/model",
+      "opencode/ spaced",
+      "opencode/ model",
+      `${"p".repeat(101)}/model`,
+    ];
+    for (const key of invalid) {
+      const raw = { agents: { "*": { fallbackModels: [key] } } };
+      const { warnings } = parseConfig(raw);
+      expect(warnings.length).toBeGreaterThan(0);
+    }
+  });
+
+  it("accepts a model ID longer than 100 characters up to 200", () => {
+    const key = `opencode/${"m".repeat(150)}`;
+    const raw = { agents: { "*": { fallbackModels: [key] } } };
+    const { config, warnings } = parseConfig(raw);
+    expect(warnings).toHaveLength(0);
+    expect(config.agents?.["*"].fallbackModels).toEqual([key]);
+  });
+
   it("rejects cooldownMs below minimum", () => {
     const raw = {
       defaults: { cooldownMs: 100 },