fix: resolve SSH commit/PR agents through login+interactive shell PATH

OpenCode and other agents installed via shell startup files (nvm/fnm/
Homebrew) could not be found when generating commit/PR messages over
SSH. The relay runs on the remote host via a non-interactive SSH command
whose PATH lacks those install dirs, so the agent binary was not found
and generation failed.

Opt the SSH commit/PR-generation spawn into login+interactive shell
(bash/zsh -ilc) PATH resolution, matching the established pattern in
hydrate-shell-path.ts and preflight-handler.ts. The interactive flag is
required so .bashrc/.zshrc PATH hooks get sourced. Windows and
non-bash/zsh shells are unchanged.

Fixes #4720

Supersedes #5197.

Co-authored-by: Andy Murray <andym3@illinois.edu>

Co-authored-by: Orca <help@stably.ai>

src/main/providers/ssh-git-provider.test.ts

@@ -382,7 +382,8 @@ describe('SshGitProvider', () => {
       cwd: '/home/user/repo',
       stdin: null,
       timeoutMs: 60_000,
-      operation: 'commit-message'
+      operation: 'commit-message',
+      shell: true
     })
     expect(result).toEqual(execResult)
   })
@@ -426,7 +427,8 @@ describe('SshGitProvider', () => {
       cwd: '/home/user/repo',
       stdin: null,
       timeoutMs: 60_000,
-      operation: 'commit-message'
+      operation: 'commit-message',
+      shell: true
     })
     expect(mux.request).toHaveBeenNthCalledWith(2, 'agent.execNonInteractive', {
       binary: 'codex',
@@ -434,7 +436,8 @@ describe('SshGitProvider', () => {
       cwd: '/home/user/repo',
       stdin: null,
       timeoutMs: 60_000,
-      operation: 'pull-request-fields'
+      operation: 'pull-request-fields',
+      shell: true
     })
 
     await provider.cancelGenerateCommitMessage('/home/user/repo')

src/main/providers/ssh-git-provider.ts

@@ -192,7 +192,10 @@ export class SshGitProvider implements IGitProvider {
         cwd,
         stdin: plan.stdinPayload,
         timeoutMs,
-        operation
+        operation,
+        // Why: commit/PR agents on SSH hosts are often installed by shell
+        // startup files, so this path opts into login-shell PATH resolution.
+        shell: true
       },
       undefined,
       operation
@@ -265,6 +268,7 @@ export class SshGitProvider implements IGitProvider {
       timeoutMs: number
       env?: Record<string, string>
       operation?: string
+      shell?: boolean
     },
     signal?: AbortSignal,
     operation?: string

src/relay/agent-exec-handler.test.ts

@@ -1,7 +1,12 @@
 import { exec, spawn } from 'child_process'
 import { beforeEach, describe, expect, it, vi } from 'vitest'
 import type * as ChildProcess from 'child_process'
-import { createFakeChild, createHandlers, requestContext } from './agent-exec-handler-test-harness'
+import {
+  createFakeChild,
+  createHandlers,
+  requestContext,
+  withPlatform
+} from './agent-exec-handler-test-harness'
 
 vi.mock('child_process', async (importOriginal) => {
   const actual = await importOriginal<typeof ChildProcess>()
@@ -97,6 +102,62 @@ describe('AgentExecHandler', () => {
     })
   })
 
+  it('uses the default POSIX shell when requested so SSH agent commands inherit shell PATH', async () => {
+    const originalShell = process.env.SHELL
+    process.env.SHELL = '/bin/bash'
+    try {
+      await withPlatform('linux', async () => {
+        const child = createFakeChild()
+        spawnMock.mockReturnValue(child as never)
+        const handlers = createHandlers()
+
+        const pending = handlers.get('agent.execNonInteractive')!(
+          {
+            binary: 'opencode',
+            args: ['run', '--model', 'opencode/deepseek-v4-flash-free'],
+            cwd: '/repo',
+            stdin: 'PROMPT',
+            timeoutMs: 5_000,
+            shell: true
+          },
+          requestContext()
+        )
+
+        child.emit('close', 0)
+
+        await expect(pending).resolves.toMatchObject({
+          exitCode: 0,
+          timedOut: false
+        })
+        expect(spawnMock).toHaveBeenCalledWith(
+          '/bin/bash',
+          [
+            '-ilc',
+            'exec "$@"',
+            '_',
+            'opencode',
+            'run',
+            '--model',
+            'opencode/deepseek-v4-flash-free'
+          ],
+          {
+            cwd: '/repo',
+            env: process.env,
+            stdio: ['pipe', 'pipe', 'pipe'],
+            windowsHide: true
+          }
+        )
+        expect(child.stdin.end).toHaveBeenCalledWith('PROMPT')
+      })
+    } finally {
+      if (originalShell === undefined) {
+        delete process.env.SHELL
+      } else {
+        process.env.SHELL = originalShell
+      }
+    }
+  })
+
   it('cancels the in-flight command for the requested cwd', async () => {
     const child = createFakeChild()
     spawnMock.mockReturnValue(child as never)

src/relay/agent-exec-handler.ts

@@ -1,7 +1,8 @@
 import { exec, spawn, type ChildProcess } from 'child_process'
 import { existsSync } from 'fs'
-import { delimiter, join } from 'path'
+import { basename, delimiter, join } from 'path'
 import type { RelayDispatcher, RequestContext } from './dispatcher'
+import { resolveDefaultShell } from './pty-shell-utils'
 
 const DEFAULT_TIMEOUT_MS = 60_000
 const MAX_TIMEOUT_MS = 5 * 60 * 1000
@@ -64,6 +65,31 @@ function getWindowsSafeSpawn(
   return { spawnCmd: getCmdExePath(), spawnArgs: ['/d', '/s', '/c', commandLine] }
 }
 
+function getSpawnPlan(
+  binary: string,
+  args: string[],
+  env: NodeJS.ProcessEnv,
+  useShell: boolean
+): { spawnCmd: string; spawnArgs: string[] } {
+  if (process.platform === 'win32' || !useShell) {
+    return getWindowsSafeSpawn(binary, args, env)
+  }
+  const shell = resolveDefaultShell()
+  const shellName = basename(shell).toLowerCase()
+  if (shellName !== 'bash' && shellName !== 'zsh') {
+    return { spawnCmd: binary, spawnArgs: args }
+  }
+  // Why: SSH relay processes are launched by a non-interactive SSH command,
+  // whose PATH often lacks nvm/fnm/Homebrew agent installs. The interactive
+  // flag (`-i`) is required so .bashrc/.zshrc — where those PATH hooks live —
+  // get sourced; a plain login shell (`-lc`) would skip them. This resolves
+  // remote agent commands like the user's Orca terminal shell does.
+  return {
+    spawnCmd: shell,
+    spawnArgs: ['-ilc', 'exec "$@"', '_', binary, ...args]
+  }
+}
+
 // Why: mirrors src/main/text-generation/commit-message-text-generation.ts. On
 // Windows, npm-installed CLIs like `claude`/`codex` are usually `.cmd` shims.
 // We route those through cmd.exe so Node can launch them, and taskkill is
@@ -95,6 +121,7 @@ type ExecParams = {
   timeoutMs: unknown
   env: unknown
   operation: unknown
+  shell: unknown
 }
 
 type CancelParams = {
@@ -169,11 +196,12 @@ export class AgentExecHandler {
         ? (params.env as Record<string, string>)
         : null
     const spawnEnv = extraEnv ? { ...process.env, ...extraEnv } : process.env
+    const useShell = params.shell === true
 
     return new Promise<ExecResult>((resolve) => {
       let child
       try {
-        const { spawnCmd, spawnArgs } = getWindowsSafeSpawn(binary, args, spawnEnv)
+        const { spawnCmd, spawnArgs } = getSpawnPlan(binary, args, spawnEnv, useShell)
         child = spawn(spawnCmd, spawnArgs, {
           cwd,
           env: spawnEnv,