feat(providers): add GitHub Copilot CLI provider

cli/index.js

@@ -2287,7 +2287,7 @@ program
   .option('--workers <n>', 'Max sub-agents for worker to spawn in parallel', parseInt)
   .option(
     '--provider <provider>',
-    'Override all agents to use a provider (claude, codex, gemini, opencode)'
+    'Override all agents to use a provider (claude, codex, gemini, opencode, copilot)'
   )
   .option('--model <model>', 'Override all agent models (provider-specific model id)')
   .option(

docs/providers.md

@@ -71,3 +71,83 @@ Mount presets in `dockerMounts` include: `codex`, `gemini`, `gcloud`, `claude`,
 
 Use `--no-mounts` to disable all credential mounts (you will get a warning if
 credentials are missing).
+
+## GitHub Copilot CLI
+
+The `copilot` provider integrates the GitHub Copilot CLI.
+
+Install:
+
+```bash
+npm install -g @github/copilot
+```
+
+Authenticate (interactive, one-time):
+
+```bash
+copilot
+# then inside the REPL:
+/login
+```
+
+Credentials are stored under `~/.copilot/`. Logs are under `~/.copilot/logs/`.
+
+Usage with zeroshot:
+
+```bash
+zeroshot run 123 --provider copilot
+```
+
+Models (level mapping):
+
+- `level1` → `gpt-5-mini`
+- `level2` → `claude-sonnet-4.5` (default)
+- `level3` → `claude-opus-4.6`
+
+Override per level via `providerSettings.copilot.levelOverrides`.
+
+Limitations:
+
+- Copilot CLI emits **plain text** with `--silent` (no structured streaming
+  JSON like Claude/Codex). Token usage is not reported, and live tool-call
+  events are not surfaced. The whole stdout stream is treated as text.
+- `jsonSchema` is supported only by **prompt-injecting** the schema (no native
+  `--output-schema` flag); reliability depends on the underlying model.
+- Thinking mode and reasoningEffort are not exposed by the CLI.
+- Auto-approval is enabled via `--allow-all` (a.k.a. `--yolo`); use isolation
+  (`--worktree` / `--docker`) when running untrusted prompts.
+
+### MCP servers
+
+Copilot CLI loads MCP servers from `~/.copilot/mcp-config.json` by default.
+zeroshot can additionally pass per-run MCP configs via the `--additional-mcp-config`
+flag. Set `providerSettings.copilot.mcpConfig` to any of:
+
+- a JSON string (raw config),
+- an object (zeroshot will `JSON.stringify` it),
+- a file path prefixed with `@` (e.g. `"@./mcp.json"`),
+- an array of any of the above (each entry emits one flag — augments, not
+  overrides, the user-level config).
+
+Example:
+
+```jsonc
+{
+  "providerSettings": {
+    "copilot": {
+      "mcpConfig": {
+        "mcpServers": {
+          "fs": {
+            "command": "npx",
+            "args": ["-y", "@modelcontextprotocol/server-filesystem", "."],
+          },
+        },
+      },
+    },
+  },
+}
+```
+
+GitHub's built-in MCP server can be tuned with `--add-github-mcp-tool` /
+`--add-github-mcp-toolset` directly in `extraArgs` if you need to override the
+default CLI subset.

lib/provider-names.js

@@ -6,9 +6,11 @@ const PROVIDER_ALIASES = {
   codex: 'codex',
   gemini: 'gemini',
   opencode: 'opencode',
+  copilot: 'copilot',
+  github: 'copilot',
 };
 
-const VALID_PROVIDERS = ['claude', 'codex', 'gemini', 'opencode'];
+const VALID_PROVIDERS = ['claude', 'codex', 'gemini', 'opencode', 'copilot'];
 
 function normalizeProviderName(name) {
   if (!name || typeof name !== 'string') return name;

src/preflight.js

@@ -428,14 +428,24 @@ function validateProvider(providerName, options) {
         'Command "opencode" not installed',
         ['Install Opencode CLI: see https://opencode.ai', 'Then run: opencode --version']
       ),
+    copilot: () =>
+      validateCliProvider(
+        'copilot',
+        'GitHub Copilot CLI not available',
+        'Command "copilot" not installed',
+        [
+          'Install Copilot CLI: npm install -g @github/copilot',
+          'Then run: copilot (and use /login inside the REPL)',
+        ]
+      ),
   };
 
   const validator = validatorByProvider[providerName];
   if (!validator) {
     return {
       errors: [
         formatError('Unknown provider', `Provider "${providerName}" is not supported`, [
-          'Use claude, codex, gemini, or opencode',
+          'Use claude, codex, gemini, opencode, or copilot',
         ]),
       ],
       warnings: [],

src/providers/capabilities.js

@@ -37,6 +37,15 @@ const CAPABILITIES = {
     thinkingMode: true,
     reasoningEffort: true,
   },
+  copilot: {
+    dockerIsolation: true,
+    worktreeIsolation: true,
+    mcpServers: true,
+    jsonSchema: 'experimental',
+    streamJson: false,
+    thinkingMode: false,
+    reasoningEffort: false,
+  },
 };
 
 function checkCapability(provider, capability) {

src/providers/copilot/cli-builder.js

@@ -0,0 +1,55 @@
+function buildCommand(context, options = {}) {
+  const { modelSpec, jsonSchema, autoApprove, mcpConfig, addDirs, cliFeatures = {} } = options;
+
+  let finalContext = context;
+  if (jsonSchema) {
+    const schemaStr =
+      typeof jsonSchema === 'string' ? jsonSchema : JSON.stringify(jsonSchema, null, 2);
+    finalContext =
+      context +
+      `\n\n## OUTPUT FORMAT (CRITICAL - REQUIRED)\n\nYou MUST respond with a JSON object that exactly matches this schema. NO markdown, NO explanation, NO code blocks. ONLY the raw JSON object.\n\nSchema:\n\`\`\`json\n${schemaStr}\n\`\`\`\n\nYour response must be ONLY valid JSON. Start with { and end with }. Nothing else.`;
+  }
+
+  const args = ['-p', finalContext];
+
+  if (cliFeatures.supportsSilent !== false) {
+    args.push('--silent');
+  }
+
+  if (autoApprove !== false && cliFeatures.supportsAllowAll !== false) {
+    args.push('--allow-all');
+  }
+
+  if (modelSpec?.model && cliFeatures.supportsModel !== false) {
+    args.push('--model', modelSpec.model);
+  }
+
+  // MCP servers — Copilot CLI augments ~/.copilot/mcp-config.json with --additional-mcp-config.
+  // Accepts either a JSON string, a config object (will be JSON.stringified),
+  // a file path prefixed with @, or an array of any of the above (each emits one flag).
+  if (mcpConfig && cliFeatures.supportsMcpConfig !== false) {
+    const entries = Array.isArray(mcpConfig) ? mcpConfig : [mcpConfig];
+    for (const entry of entries) {
+      if (entry === null || entry === undefined) continue;
+      const value = typeof entry === 'string' ? entry : JSON.stringify(entry);
+      args.push('--additional-mcp-config', value);
+    }
+  }
+
+  // Allow extra directories for file access (useful when running outside cwd)
+  if (Array.isArray(addDirs) && cliFeatures.supportsAddDir !== false) {
+    for (const dir of addDirs) {
+      if (typeof dir === 'string' && dir) args.push('--add-dir', dir);
+    }
+  }
+
+  return {
+    binary: 'copilot',
+    args,
+    env: {},
+  };
+}
+
+module.exports = {
+  buildCommand,
+};

src/providers/copilot/index.js

@@ -0,0 +1,106 @@
+const BaseProvider = require('../base-provider');
+const { commandExists, getCommandPath, getHelpOutput } = require('../../../lib/provider-detection');
+const { buildCommand } = require('./cli-builder');
+const { parseEvent } = require('./output-parser');
+const {
+  MODEL_CATALOG,
+  LEVEL_MAPPING,
+  DEFAULT_LEVEL,
+  DEFAULT_MAX_LEVEL,
+  DEFAULT_MIN_LEVEL,
+} = require('./models');
+
+const warned = new Set();
+
+class CopilotProvider extends BaseProvider {
+  constructor() {
+    super({ name: 'copilot', displayName: 'Copilot', cliCommand: 'copilot' });
+    this._cliFeatures = null;
+  }
+
+  isAvailable() {
+    return commandExists(this.cliCommand);
+  }
+
+  getCliPath() {
+    return getCommandPath(this.cliCommand) || this.cliCommand;
+  }
+
+  getInstallInstructions() {
+    return 'npm install -g @github/copilot';
+  }
+
+  getAuthInstructions() {
+    return 'Run `copilot` then type `/login` (requires a GitHub account with Copilot access).';
+  }
+
+  getCliFeatures() {
+    if (this._cliFeatures) return this._cliFeatures;
+    const help = getHelpOutput(this.cliCommand, []);
+    const unknown = !help;
+
+    const features = {
+      supportsModel: unknown ? true : /--model\b/.test(help),
+      supportsAllowAll: unknown ? true : /--allow-all\b|--yolo\b/.test(help),
+      supportsSilent: unknown ? true : /--silent\b/.test(help),
+      supportsNoCustomInstructions: unknown ? true : /--no-custom-instructions\b/.test(help),
+      supportsAutoApprove: unknown ? true : /--allow-all\b|--yolo\b/.test(help),
+      supportsMcpConfig: unknown ? true : /--additional-mcp-config\b/.test(help),
+      supportsAddDir: unknown ? true : /--add-dir\b/.test(help),
+      supportsConfigDir: unknown ? true : /--config-dir\b/.test(help),
+      unknown,
+    };
+
+    this._cliFeatures = features;
+    return features;
+  }
+
+  getCredentialPaths() {
+    return ['~/.copilot'];
+  }
+
+  buildCommand(context, options) {
+    const cliFeatures = options.cliFeatures || this.getCliFeatures();
+
+    if (options.modelSpec?.model && cliFeatures.supportsModel === false) {
+      this._warnOnce(
+        'copilot-model',
+        'Copilot CLI help did not advertise --model; passing it anyway may fail.'
+      );
+    }
+
+    return buildCommand(context, { ...options, cliFeatures });
+  }
+
+  parseEvent(line) {
+    return parseEvent(line);
+  }
+
+  getModelCatalog() {
+    return MODEL_CATALOG;
+  }
+
+  getLevelMapping() {
+    return LEVEL_MAPPING;
+  }
+
+  getDefaultLevel() {
+    return DEFAULT_LEVEL;
+  }
+
+  getDefaultMaxLevel() {
+    return DEFAULT_MAX_LEVEL;
+  }
+
+  getDefaultMinLevel() {
+    return DEFAULT_MIN_LEVEL;
+  }
+
+  _warnOnce(key, message) {
+    if (warned.has(key)) return;
+    warned.add(key);
+    console.warn(`⚠️ ${message}`);
+  }
+}
+
+module.exports = CopilotProvider;

src/providers/copilot/models.js

@@ -0,0 +1,24 @@
+const MODEL_CATALOG = {
+  'gpt-5-mini': { rank: 1 },
+  'gpt-5': { rank: 2 },
+  'claude-sonnet-4.5': { rank: 2 },
+  'claude-opus-4.6': { rank: 3 },
+};
+
+const LEVEL_MAPPING = {
+  level1: { rank: 1, model: 'gpt-5-mini', reasoningEffort: null },
+  level2: { rank: 2, model: 'claude-sonnet-4.5', reasoningEffort: null },
+  level3: { rank: 3, model: 'claude-opus-4.6', reasoningEffort: null },
+};
+
+const DEFAULT_LEVEL = 'level2';
+const DEFAULT_MAX_LEVEL = 'level3';
+const DEFAULT_MIN_LEVEL = 'level1';
+
+module.exports = {
+  MODEL_CATALOG,
+  LEVEL_MAPPING,
+  DEFAULT_LEVEL,
+  DEFAULT_MAX_LEVEL,
+  DEFAULT_MIN_LEVEL,
+};