diff --git a/agents/index.ts b/agents/index.ts
index d5e08fa..ce7f798 100644
--- a/agents/index.ts
+++ b/agents/index.ts
@@ -3,6 +3,7 @@ import { claude } from "./claude.ts";
 import { codex } from "./codex.ts";
 import { cursor } from "./cursor.ts";
 import { gemini } from "./gemini.ts";
+import { opencode } from "./opencode.ts";
 import type { Agent } from "./shared.ts";
 
 export const agents = {
@@ -10,4 +11,5 @@ export const agents = {
   codex,
   cursor,
   gemini,
+  opencode,
 } satisfies Record<AgentName, Agent>;
diff --git a/agents/opencode.ts b/agents/opencode.ts
new file mode 100644
index 0000000..22026ac
--- /dev/null
+++ b/agents/opencode.ts
@@ -0,0 +1,391 @@
+import { existsSync, mkdirSync, readFileSync, writeFileSync } from "node:fs";
+import { join } from "node:path";
+import { log } from "../utils/cli.ts";
+import { spawn } from "../utils/subprocess.ts";
+import { addInstructions } from "./instructions.ts";
+import {
+  agent,
+  type ConfigureMcpServersParams,
+  createAgentEnv,
+  installFromNpmTarball,
+  setupProcessAgentEnv,
+} from "./shared.ts";
+
+// opencode cli event types inferred from json output format
+interface OpenCodeInitEvent {
+  type: "init";
+  timestamp?: string;
+  session_id?: string;
+  model?: string;
+  [key: string]: unknown;
+}
+
+interface OpenCodeMessageEvent {
+  type: "message";
+  timestamp?: string;
+  role?: "user" | "assistant";
+  content?: string;
+  delta?: boolean;
+  [key: string]: unknown;
+}
+
+interface OpenCodeTextEvent {
+  type: "text";
+  timestamp?: string;
+  sessionID?: string;
+  part?: {
+    id?: string;
+    type?: string;
+    text?: string;
+    [key: string]: unknown;
+  };
+  [key: string]: unknown;
+}
+
+interface OpenCodeStepStartEvent {
+  type: "step_start";
+  timestamp?: string;
+  sessionID?: string;
+  part?: {
+    id?: string;
+    type?: string;
+    [key: string]: unknown;
+  };
+  [key: string]: unknown;
+}
+
+interface OpenCodeStepFinishEvent {
+  type: "step_finish";
+  timestamp?: string;
+  sessionID?: string;
+  part?: {
+    id?: string;
+    type?: string;
+    reason?: string;
+    cost?: number;
+    tokens?: {
+      input?: number;
+      output?: number;
+      reasoning?: number;
+      cache?: {
+        read?: number;
+        write?: number;
+      };
+    };
+    [key: string]: unknown;
+  };
+  [key: string]: unknown;
+}
+
+interface OpenCodeToolUseEvent {
+  type: "tool_use";
+  timestamp?: string;
+  tool_name?: string;
+  tool_id?: string;
+  parameters?: unknown;
+  [key: string]: unknown;
+}
+
+interface OpenCodeToolResultEvent {
+  type: "tool_result";
+  timestamp?: string;
+  tool_id?: string;
+  status?: "success" | "error";
+  output?: string;
+  [key: string]: unknown;
+}
+
+interface OpenCodeResultEvent {
+  type: "result";
+  timestamp?: string;
+  status?: "success" | "error";
+  stats?: {
+    total_tokens?: number;
+    input_tokens?: number;
+    output_tokens?: number;
+    duration_ms?: number;
+    tool_calls?: number;
+  };
+  [key: string]: unknown;
+}
+
+type OpenCodeEvent =
+  | OpenCodeInitEvent
+  | OpenCodeMessageEvent
+  | OpenCodeTextEvent
+  | OpenCodeStepStartEvent
+  | OpenCodeStepFinishEvent
+  | OpenCodeToolUseEvent
+  | OpenCodeToolResultEvent
+  | OpenCodeResultEvent;
+
+let finalOutput = "";
+let accumulatedTokens: { input: number; output: number } = { input: 0, output: 0 };
+let tokensLogged = false;
+
+const messageHandlers = {
+  init: (_event: OpenCodeInitEvent) => {
+    // initialization event - reset state
+    finalOutput = "";
+    accumulatedTokens = { input: 0, output: 0 };
+    tokensLogged = false;
+  },
+  message: (event: OpenCodeMessageEvent) => {
+    // update finalOutput but don't log here - text handler will log
+    if (event.role === "assistant" && event.content?.trim() && !event.delta) {
+      const message = event.content.trim();
+      if (message) {
+        finalOutput = message;
+      }
+    }
+  },
+  text: (event: OpenCodeTextEvent) => {
+    // log from text events only to avoid duplicates
+    if (event.part?.text?.trim()) {
+      const message = event.part.text.trim();
+      log.box(message, { title: "OpenCode" });
+      finalOutput = message;
+    }
+  },
+  step_start: (_event: OpenCodeStepStartEvent) => {
+    // step start - no logging needed
+  },
+  step_finish: async (event: OpenCodeStepFinishEvent) => {
+    // accumulate tokens from step_finish events (they come here, not in result)
+    const eventTokens = event.part?.tokens;
+    if (eventTokens) {
+      const inputTokens = eventTokens.input || 0;
+      const outputTokens = eventTokens.output || 0;
+
+      // accumulate tokens (don't log yet - wait for result event)
+      accumulatedTokens.input += inputTokens;
+      accumulatedTokens.output += outputTokens;
+    }
+  },
+  tool_use: (event: OpenCodeToolUseEvent) => {
+    if (event.tool_name) {
+      log.toolCall({
+        toolName: event.tool_name,
+        input: event.parameters || {},
+      });
+    }
+  },
+  tool_result: (event: OpenCodeToolResultEvent) => {
+    if (event.status === "error") {
+      const errorMsg =
+        typeof event.output === "string" ? event.output : JSON.stringify(event.output);
+      log.warning(`Tool call failed: ${errorMsg}`);
+    }
+  },
+  result: async (event: OpenCodeResultEvent) => {
+    if (event.status === "error") {
+      log.error(`OpenCode CLI failed: ${JSON.stringify(event)}`);
+    } else {
+      // log tokens once at the end (use stats from result if available, otherwise use accumulated from step_finish)
+      const inputTokens = event.stats?.input_tokens || accumulatedTokens.input || 0;
+      const outputTokens = event.stats?.output_tokens || accumulatedTokens.output || 0;
+      const totalTokens = event.stats?.total_tokens || inputTokens + outputTokens;
+
+      if ((inputTokens > 0 || outputTokens > 0) && !tokensLogged) {
+        await log.summaryTable([
+          [
+            { data: "Input Tokens", header: true },
+            { data: "Output Tokens", header: true },
+            { data: "Total Tokens", header: true },
+          ],
+          [String(inputTokens), String(outputTokens), String(totalTokens)],
+        ]);
+        tokensLogged = true;
+      }
+    }
+  },
+};
+
+export const opencode = agent({
+  name: "opencode",
+  install: async () => {
+    return await installFromNpmTarball({
+      packageName: "opencode-ai",
+      version: "latest",
+      executablePath: "bin/opencode",
+      installDependencies: true,
+    });
+  },
+  run: async ({ payload, apiKey, mcpServers, cliPath }) => {
+    // 1. configure home/config directory
+    const tempHome = process.env.PULLFROG_TEMP_DIR!;
+    const configDir = join(tempHome, ".config", "opencode");
+    mkdirSync(configDir, { recursive: true });
+
+    // 2. initialize MCP servers and sandbox
+    configureOpenCodeMcpServers({ mcpServers });
+    configureOpenCodeSandbox({ sandbox: payload.sandbox ?? false });
+
+    if (!apiKey) {
+      throw new Error("anthropic_api_key is required for opencode agent");
+    }
+
+    // 3. prepare prompt and args
+    const prompt = addInstructions(payload);
+    const args = ["run", "--format", "json", "-m", "anthropic/claude-sonnet-4-20250514", prompt];
+
+    if (payload.sandbox) {
+      log.info("🔒 sandbox mode enabled: restricting to read-only operations");
+    }
+
+    // 4. set up environment
+    const packageDir = join(cliPath, "..", "..");
+    setupProcessAgentEnv({ ANTHROPIC_API_KEY: apiKey, HOME: tempHome });
+    const env = createAgentEnv({ ANTHROPIC_API_KEY: apiKey, HOME: tempHome });
+
+    // 5. spawn and stream JSON output
+    let output = "";
+    const result = await spawn({
+      cmd: cliPath,
+      args,
+      cwd: packageDir,
+      env,
+      timeout: 300000,
+      stdio: ["ignore", "pipe", "pipe"],
+      onStdout: async (chunk) => {
+        const text = chunk.toString();
+        output += text;
+
+        // parse each line as JSON (opencode outputs one JSON object per line)
+        const lines = text.split("\n");
+        for (const line of lines) {
+          const trimmed = line.trim();
+          if (!trimmed) {
+            continue;
+          }
+
+          try {
+            const event = JSON.parse(trimmed) as OpenCodeEvent;
+            const handler = messageHandlers[event.type as keyof typeof messageHandlers];
+            if (handler) {
+              await handler(event as never);
+            }
+          } catch {
+            // non-JSON lines are ignored
+          }
+        }
+      },
+      onStderr: (chunk) => {
+        const trimmed = chunk.trim();
+        if (trimmed) {
+          log.warning(trimmed);
+        }
+      },
+    });
+
+    // 6. log tokens if they weren't logged yet (fallback if result event wasn't emitted)
+    if (!tokensLogged && (accumulatedTokens.input > 0 || accumulatedTokens.output > 0)) {
+      const totalTokens = accumulatedTokens.input + accumulatedTokens.output;
+      await log.summaryTable([
+        [
+          { data: "Input Tokens", header: true },
+          { data: "Output Tokens", header: true },
+          { data: "Total Tokens", header: true },
+        ],
+        [String(accumulatedTokens.input), String(accumulatedTokens.output), String(totalTokens)],
+      ]);
+    }
+
+    // 7. return result
+    return {
+      success: result.exitCode === 0,
+      output: finalOutput || output,
+      error: result.exitCode !== 0 ? result.stderr : undefined,
+    };
+  },
+});
+
+/**
+ * Configure MCP servers for OpenCode using opencode.json config file.
+ * OpenCode uses opencode.json with mcp section supporting remote servers with type: "remote" and url.
+ */
+function configureOpenCodeMcpServers({
+  mcpServers,
+}: {
+  mcpServers: ConfigureMcpServersParams["mcpServers"];
+}): void {
+  const tempHome = process.env.PULLFROG_TEMP_DIR!;
+  const configDir = join(tempHome, ".config", "opencode");
+  mkdirSync(configDir, { recursive: true });
+  const configPath = join(configDir, "opencode.json");
+
+  // convert to opencode's expected format
+  const opencodeMcpServers: Record<string, { type: "remote"; url: string; enabled?: boolean }> = {};
+  for (const [serverName, serverConfig] of Object.entries(mcpServers)) {
+    if (serverConfig.type !== "http") {
+      throw new Error(
+        `Unsupported MCP server type for OpenCode: ${(serverConfig as any).type || "unknown"}`
+      );
+    }
+
+    opencodeMcpServers[serverName] = {
+      type: "remote",
+      url: serverConfig.url,
+      enabled: true,
+    };
+  }
+
+  // read existing config if it exists, or create new one
+  let config: Record<string, unknown> = {};
+  try {
+    if (existsSync(configPath)) {
+      const existingConfig = readFileSync(configPath, "utf-8");
+      config = JSON.parse(existingConfig);
+    }
+  } catch {
+    // config doesn't exist yet or is invalid, start fresh
+  }
+
+  config.mcp = opencodeMcpServers;
+
+  writeFileSync(configPath, JSON.stringify(config, null, 2), "utf-8");
+  log.info(`MCP config written to ${configPath}`);
+}
+
+/**
+ * Configure OpenCode sandbox mode via opencode.json.
+ * When sandbox is enabled, restricts tools to read-only operations.
+ */
+function configureOpenCodeSandbox({ sandbox }: { sandbox: boolean }): void {
+  const tempHome = process.env.PULLFROG_TEMP_DIR!;
+  const configDir = join(tempHome, ".config", "opencode");
+  mkdirSync(configDir, { recursive: true });
+  const configPath = join(configDir, "opencode.json");
+
+  // read existing config if it exists, or create new one
+  let config: Record<string, unknown> = {};
+  try {
+    if (existsSync(configPath)) {
+      const existingConfig = readFileSync(configPath, "utf-8");
+      config = JSON.parse(existingConfig);
+    }
+  } catch {
+    // config doesn't exist yet or is invalid, start fresh
+  }
+
+  if (sandbox) {
+    // sandbox mode: disable write, bash, and webfetch tools
+    config.tools = {
+      write: false,
+      bash: false,
+      webfetch: false,
+    };
+  } else {
+    // normal mode: enable all tools (or don't set tools config to use defaults)
+    config.tools = {
+      write: true,
+      bash: true,
+      webfetch: true,
+    };
+  }
+
+  // preserve MCP config if it was already set by configureOpenCodeMcpServers
+  // (this function is called after configureOpenCodeMcpServers, so MCP config should already exist)
+  writeFileSync(configPath, JSON.stringify(config, null, 2), "utf-8");
+  log.info(`OpenCode config written to ${configPath} (sandbox: ${sandbox})`);
+}
diff --git a/agents/shared.ts b/agents/shared.ts
index dbc9578..26e180a 100644
--- a/agents/shared.ts
+++ b/agents/shared.ts
@@ -96,6 +96,17 @@ export interface InstallFromGithubParams {
   githubInstallationToken?: string;
 }
 
+/**
+ * Parameters for installing from GitHub releases tarball
+ */
+export interface InstallFromGithubTarballParams {
+  owner: string;
+  repo: string;
+  assetNamePattern: string;
+  executablePath: string;
+  githubInstallationToken?: string;
+}
+
 /**
  * NPM registry response data structure
  */
@@ -318,6 +329,92 @@ export async function installFromGithub({
   return cliPath;
 }
 
+/**
+ * Install a CLI tool from a GitHub release tarball
+ * Downloads the tar.gz from GitHub releases, extracts it, and returns the path to the CLI executable
+ * The temp directory will be cleaned up by the OS automatically
+ */
+export async function installFromGithubTarball({
+  owner,
+  repo,
+  assetNamePattern,
+  executablePath,
+  githubInstallationToken,
+}: InstallFromGithubTarballParams): Promise<string> {
+  log.info(`📦 Installing ${owner}/${repo} from GitHub releases...`);
+
+  // determine platform-specific asset name
+  const os = process.platform === "darwin" ? "darwin" : "linux";
+  const arch = process.arch === "arm64" ? "arm64" : "x64";
+  const assetName = assetNamePattern.replace("{os}", os).replace("{arch}", arch);
+
+  // fetch release from GitHub API (latest)
+  const releaseUrl = `https://api.github.com/repos/${owner}/${repo}/releases/latest`;
+  log.info(`Fetching release from ${releaseUrl}...`);
+
+  const headers: Record<string, string> = {};
+  if (githubInstallationToken) {
+    headers.Authorization = `Bearer ${githubInstallationToken}`;
+  }
+
+  const releaseResponse = await fetchWithRetry(releaseUrl, headers, "Failed to fetch release");
+
+  const releaseData = (await releaseResponse.json()) as {
+    tag_name: string;
+    assets: Array<{
+      name: string;
+      browser_download_url: string;
+    }>;
+  };
+
+  log.info(`Found release: ${releaseData.tag_name}`);
+
+  const asset = releaseData.assets.find((a) => a.name === assetName);
+  if (!asset) {
+    throw new Error(`Asset '${assetName}' not found in release ${releaseData.tag_name}`);
+  }
+  const assetUrl = asset.browser_download_url;
+
+  log.info(`Downloading asset from ${assetUrl}...`);
+
+  const tempDir = process.env.PULLFROG_TEMP_DIR!;
+  const tarballPath = join(tempDir, assetName);
+
+  // download the asset
+  const assetResponse = await fetchWithRetry(assetUrl, headers, "Failed to download asset");
+
+  if (!assetResponse.body) throw new Error("Response body is null");
+  const fileStream = createWriteStream(tarballPath);
+  await pipeline(assetResponse.body, fileStream);
+  log.info(`Downloaded tarball to ${tarballPath}`);
+
+  // extract tar.gz
+  log.info(`Extracting tarball...`);
+  const extractResult = spawnSync("tar", ["-xzf", tarballPath, "-C", tempDir], {
+    stdio: "pipe",
+    encoding: "utf-8",
+  });
+  if (extractResult.status !== 0) {
+    throw new Error(
+      `Failed to extract tarball: ${extractResult.stderr || extractResult.stdout || "Unknown error"}`
+    );
+  }
+
+  // find executable in the extracted tarball
+  const cliPath = join(tempDir, executablePath);
+
+  if (!existsSync(cliPath)) {
+    throw new Error(`Executable not found in extracted tarball at ${cliPath}`);
+  }
+
+  // make the file executable
+  chmodSync(cliPath, 0o755);
+
+  log.info(`✓ ${owner}/${repo} installed at ${cliPath}`);
+
+  return cliPath;
+}
+
 /**
  * Install a CLI tool from a curl-based install script
  * Downloads the install script, runs it with HOME set to temp directory, and returns the path to the CLI executable
diff --git a/external.ts b/external.ts
index e65a2e3..f089a5f 100644
--- a/external.ts
+++ b/external.ts
@@ -38,6 +38,11 @@ export const agentsManifest = {
     apiKeyNames: ["google_api_key", "gemini_api_key"],
     url: "https://ai.google.dev/gemini-api/docs",
   },
+  opencode: {
+    displayName: "OpenCode",
+    apiKeyNames: ["anthropic_api_key"],
+    url: "https://opencode.ai",
+  },
 } as const satisfies Record<string, AgentManifest>;
 
 // agent name type - union of agent slugs
diff --git a/fixtures/basic.txt b/fixtures/basic.txt
index 7dbf2b9..b1f5d4a 100644
--- a/fixtures/basic.txt
+++ b/fixtures/basic.txt
@@ -1,3 +1 @@
-Add an empty commit to https://github.com/pullfrog/pullfrog/pull/5
-
-And push it
\ No newline at end of file
+say hello
\ No newline at end of file
diff --git a/utils/subprocess.ts b/utils/subprocess.ts
index 04916c7..d3c9c6d 100644
--- a/utils/subprocess.ts
+++ b/utils/subprocess.ts
@@ -7,6 +7,7 @@ export interface SpawnOptions {
   input?: string;
   timeout?: number;
   cwd?: string;
+  stdio?: ("pipe" | "ignore" | "inherit")[];
   onStdout?: (chunk: string) => void;
   onStderr?: (chunk: string) => void;
 }
@@ -22,7 +23,7 @@ export interface SpawnResult {
  * Spawn a subprocess with streaming callbacks and buffered results
  */
 export async function spawn(options: SpawnOptions): Promise<SpawnResult> {
-  const { cmd, args, env, input, timeout, cwd, onStdout, onStderr } = options;
+  const { cmd, args, env, input, timeout, cwd, stdio, onStdout, onStderr } = options;
 
   const startTime = Date.now();
   let stdoutBuffer = "";
@@ -35,7 +36,7 @@ export async function spawn(options: SpawnOptions): Promise<SpawnResult> {
         PATH: process.env.PATH || "",
         HOME: process.env.HOME || "",
       },
-      stdio: ["pipe", "pipe", "pipe"],
+      stdio: stdio || ["pipe", "pipe", "pipe"],
       cwd: cwd || process.cwd(),
     });
 
@@ -106,7 +107,7 @@ export async function spawn(options: SpawnOptions): Promise<SpawnResult> {
       });
     });
 
-    if (input && child.stdin) {
+    if (input && child.stdin && stdio?.[0] !== "ignore") {
       child.stdin.write(input);
       child.stdin.end();
     }