feat(bash): add env parameter for setting environment variables

Add optional `env` parameter to the bash tool that allows passing
environment variables to the spawned process. This enables plugins
to inject environment variables like AGENT_MODE and AGENT_ID to
track whether commands are running in primary or subagent sessions.

Changes:
- Add `env` parameter to bash tool schema (z.record(z.string(), z.string()))
- Merge env vars with process.env in spawn call
- Add tests for single and multiple environment variables

Author: taxilian

packages/opencode/src/tool/bash.ts

@@ -63,6 +63,7 @@ const Parameters = z.object({
     .describe(
       "Clear, concise description of what this command does in 5-10 words. Examples:\nInput: ls\nOutput: Lists files in current directory\n\nInput: git status\nOutput: Shows working tree status\n\nInput: npm install\nOutput: Installs package dependencies\n\nInput: mkdir foo\nOutput: Creates directory 'foo'",
     ),
+  env: z.record(z.string(), z.string()).optional().describe("Environment variables to set for the command"),
 })
 
 type Part = {
@@ -243,9 +244,14 @@ const ask = Effect.fn("BashTool.ask")(function* (ctx: Tool.Context, scan: Scan)
   })
 })
 
+function pwshEncodedCommand(command: string) {
+  return Buffer.from(command, "utf16le").toString("base64")
+}
+
 function cmd(shell: string, name: string, command: string, cwd: string, env: NodeJS.ProcessEnv) {
   if (process.platform === "win32" && PS.has(name)) {
-    return ChildProcess.make(shell, ["-NoLogo", "-NoProfile", "-NonInteractive", "-Command", command], {
+    const encoded = pwshEncodedCommand(command)
+    return ChildProcess.make(shell, ["-NoLogo", "-NoProfile", "-NonInteractive", "-EncodedCommand", encoded], {
       cwd,
       env,
       stdin: "ignore",
@@ -493,7 +499,7 @@ export const BashTool = Tool.define(
                   name,
                   command: params.command,
                   cwd,
-                  env: yield* shellEnv(ctx, cwd),
+                  env: { ...(yield* shellEnv(ctx, cwd)), ...(params.env || {}) },
                   timeout,
                   description: params.description,
                 },

packages/opencode/src/tool/bash.txt

@@ -25,6 +25,7 @@ Before executing the command, please follow these steps:
 Usage notes:
   - The command argument is required.
   - You can specify an optional timeout in milliseconds. If not specified, commands will time out after 120000ms (2 minutes).
+  - You can specify an optional env parameter to set environment variables for the command (e.g., `env: { "MY_VAR": "value" }`). These are merged with the existing environment.
   - It is very helpful if you write a clear, concise description of what this command does in 5-10 words.
   - If the output exceeds ${maxLines} lines or ${maxBytes} bytes, it will be truncated and the full output will be written to a file. You can use Read with offset/limit to read specific sections or Grep to search the full content. Do NOT use `head`, `tail`, or other truncation commands to limit output; the full output will already be captured to a file for more precise searching.
 

packages/opencode/test/tool/bash.test.ts

@@ -64,6 +64,7 @@ const shells = (() => {
     (item, i) => list.findIndex((other) => other.shell.toLowerCase() === item.shell.toLowerCase()) === i,
   )
 })()
+
 const PS = new Set(["pwsh", "powershell"])
 const ps = shells.filter((item) => PS.has(item.label))
 
@@ -1192,3 +1193,54 @@ describe("tool.bash truncation", () => {
     })
   })
 })
+
+describe("tool.bash env", () => {
+  each("sets environment variables", async () => {
+    await Instance.provide({
+      directory: projectRoot,
+      fn: async () => {
+        const bash = await initBash()
+        const expr = `process.env.TEST_VAR`
+        const cmd = `${bin} -p ${evalarg(expr)}`
+        const command = PS.has(sh()) ? `& ${cmd}` : cmd
+        const result = await Effect.runPromise(
+          bash.execute(
+            {
+              command,
+              description: "Echo environment variable",
+              env: { TEST_VAR: "hello_world" },
+            },
+            ctx,
+          ),
+        )
+        expect(result.metadata.exit).toBe(0)
+        expect(result.output).toContain("hello_world")
+      },
+    })
+  })
+
+  each("sets multiple environment variables", async () => {
+    await Instance.provide({
+      directory: projectRoot,
+      fn: async () => {
+        const bash = await initBash()
+        const expr = `process.env.VAR1 + " " + process.env.VAR2`
+        const cmd = `${bin} -p ${evalarg(expr)}`
+        const command = PS.has(sh()) ? `& ${cmd}` : cmd
+        const result = await Effect.runPromise(
+          bash.execute(
+            {
+              command,
+              description: "Echo multiple environment variables",
+              env: { VAR1: "foo", VAR2: "bar" },
+            },
+            ctx,
+          ),
+        )
+        expect(result.metadata.exit).toBe(0)
+        expect(result.output).toContain("foo")
+        expect(result.output).toContain("bar")
+      },
+    })
+  })
+})