fix: add shell:true for Windows .cmd file spawn by nbalzotti · Pull Request #9 · unixfox/opencode-claude-code-plugin

nbalzotti · 2026-04-14T08:19:30Z

Problem

On Windows, the Claude CLI is installed as claude.cmd (a batch file wrapper). Node.js's child_process.spawn() requires shell: true to execute .cmd files — without it, spawn throws EINVAL silently.

The plugin catches this error in the session manager but only logs it at debug level (which is disabled by default). The result: the CLI process never starts, OpenCode receives an empty response, and Claude Code appears to "do nothing."

Fix

Add shell: process.platform === "win32" to both spawn() call sites:

session-manager.ts (persistent session spawning)
claude-code-language-model.ts (one-shot doGenerate calls)

The condition is platform-gated so Unix systems are unaffected.

Testing

Verified on Windows 11 (Node.js v24.13.0):

Before: spawn EINVAL → empty response → "Opus does nothing"
After: Claude Code Opus responds correctly in ~2.5s

On Windows, spawn() with a .cmd file path (e.g. claude.cmd) throws EINVAL without shell:true. This causes the plugin to silently fail — the CLI process never starts, and OpenCode receives an empty response. Uses process.platform === "win32" to only enable shell mode on Windows, avoiding unnecessary shell overhead on Unix. Fixes both spawn sites: session-manager (persistent sessions) and claude-code-language-model (doGenerate one-shot calls).

- Add mcpConfigPath to config/settings types, pass --mcp-config flag - Filter empty text blocks in message-builder to prevent API errors - Update LanguageModelV2Usage to new nested format (inputTokens.total/cacheRead) - Replace empty user message with "Continue." to avoid cache_control errors Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Copilot

Pull request overview

This PR primarily targets Windows compatibility for launching the Claude CLI by adjusting child_process.spawn() options, so .cmd shims can be executed successfully on win32. It also includes several additional functional changes (new config option, message-building behavior, and usage-shape changes) that expand the scope beyond the PR description.

Changes:

Enable shell: process.platform === "win32" for Claude CLI subprocess spawning in both persistent-session and one-shot execution paths.
Add an optional mcpConfigPath configuration value and plumb it through to CLI args (--mcp-config).
Modify prompt/message construction to drop empty text parts and send a synthetic "Continue." message when no content is produced; adjust usage object shaping/casting.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
src/types.ts	Adds `mcpConfigPath` to public config/settings types.
src/session-manager.ts	Uses `shell` on Windows for spawn; adds `--mcp-config` arg support.
src/message-builder.ts	Skips empty text parts; changes fallback message to `"Continue."`.
src/index.ts	Passes `mcpConfigPath` from provider settings into model config.
src/claude-code-language-model.ts	Uses `shell` on Windows for spawn; passes `mcpConfigPath`; changes `usage` shaping and adds type casts.

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Copilot · 2026-04-16T02:08:15Z

  const proc = spawn(cliPath, cliArgs, {
    cwd,
    stdio: ["pipe", "pipe", "pipe"],
+    shell: process.platform === "win32",
    env: { ...process.env, TERM: "xterm-256color" },


On Windows, enabling shell: true changes argument handling and can introduce command-injection/quoting issues if any CLI args (e.g., --model, paths) contain shell metacharacters or spaces. Consider avoiding shell unless the target is actually a .cmd shim (e.g., detect/resolve the real executable), or use a Windows-safe spawn helper that properly escapes arguments when invoking cmd.exe.

Copilot · 2026-04-16T02:08:15Z

    const proc = spawn(this.config.cliPath, cliArgs, {
      cwd,
      stdio: ["pipe", "pipe", "pipe"],
+      shell: process.platform === "win32",
      env: { ...process.env, TERM: "xterm-256color" },
    })



Same concern as the session manager: shell: process.platform === "win32" can change quoting semantics and allow shell interpretation of arguments. Prefer a .cmd-specific execution path (or an escaping helper) so only the Windows shim case uses a shell and arguments remain safely escaped.

Suggested change

const proc = spawn(this.config.cliPath, cliArgs, {

cwd,

stdio: ["pipe", "pipe", "pipe"],

shell: process.platform === "win32",

env: { ...process.env, TERM: "xterm-256color" },

})

const isWindowsCmdShim =

process.platform === "win32" &&

/\.(cmd|bat)$/i.test(this.config.cliPath)

const escapeForCmdExe = (value: string): string => {

const escapedForQuotes = value.replace(/"/g, '""')

const escapedMetaChars = escapedForQuotes.replace(

/([()%!^"<>&|])/g,

"^$1",

)

return `"${escapedMetaChars}"`

}

const proc = isWindowsCmdShim

? spawn(process.env.ComSpec ?? "cmd.exe", [

"/d",

"/s",

"/c",

`${escapeForCmdExe(this.config.cliPath)} ${cliArgs

.map((arg) => escapeForCmdExe(arg))

.join(" ")}`,

], {

cwd,

stdio: ["pipe", "pipe", "pipe"],

shell: false,

env: { ...process.env, TERM: "xterm-256color" },

})

: spawn(this.config.cliPath, cliArgs, {

cwd,

stdio: ["pipe", "pipe", "pipe"],

shell: false,

env: { ...process.env, TERM: "xterm-256color" },

})

Copilot · 2026-04-16T02:08:15Z

 export interface ClaudeCodeConfig {
  provider: string
  cliPath: string
  cwd?: string
  skipPermissions?: boolean
+  mcpConfigPath?: string
 }

 export interface ClaudeCodeProviderSettings {
  cliPath?: string
  cwd?: string
  name?: string
  skipPermissions?: boolean
+  mcpConfigPath?: string
 }


This PR introduces a new public config surface (mcpConfigPath) that isn’t mentioned in the PR description and isn’t documented in the README configuration section. Either update the PR description/docs accordingly, or split these changes into a separate PR to keep the Windows spawn fix scoped and reviewable.

Copilot · 2026-04-16T02:08:16Z

  if (content.length === 0) {
    return JSON.stringify({
      type: "user",
      message: {
        role: "user",
-        content: [{ type: "text", text: "" }],
+        content: [{ type: "text", text: "Continue." }],
      },
    })
  }


The new behavior here (dropping empty text parts and emitting a synthetic "Continue." message) is a functional change unrelated to the Windows .cmd spawning fix described in the PR. Please either justify it in the PR description (including the motivating bug) and add coverage, or move it into a separate PR to avoid scope creep.

Copilot · 2026-04-16T02:08:16Z

+          inputTokens: { total: 0, noCache: 0, cacheRead: undefined, cacheWrite: undefined },
+          outputTokens: { total: 0, text: undefined, reasoning: undefined },
+        } as unknown as LanguageModelV2Usage,


The usage shape is being changed and then forced through with as unknown as LanguageModelV2Usage, which bypasses type safety and may break downstream consumers expecting the previous runtime shape. Prefer constructing a LanguageModelV2Usage value that type-checks without double-casting (or keep the prior shape) and ensure the change is intentional/documented since it’s outside the PR’s stated scope.

Suggested change

inputTokens: { total: 0, noCache: 0, cacheRead: undefined, cacheWrite: undefined },

outputTokens: { total: 0, text: undefined, reasoning: undefined },

} as unknown as LanguageModelV2Usage,

inputTokens: 0,

outputTokens: 0,

totalTokens: 0,

},

nbalzotti and others added 2 commits April 14, 2026 01:19

unixfox requested a review from Copilot April 16, 2026 02:03

Copilot AI reviewed Apr 16, 2026

View reviewed changes

khalilgharbaoui mentioned this pull request Apr 24, 2026

feat: selective tool proxying, session isolation, MCP bridging, and streaming fixes #16

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fix: add shell:true for Windows .cmd file spawn#9

fix: add shell:true for Windows .cmd file spawn#9
nbalzotti wants to merge 2 commits into
unixfox:masterfrom
nbalzotti:fix/windows-spawn-shell

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-    const proc = spawn(this.config.cliPath, cliArgs, {
-      cwd,
-      stdio: ["pipe", "pipe", "pipe"],
-      shell: process.platform === "win32",
-      env: { ...process.env, TERM: "xterm-256color" },
-    })
+    const isWindowsCmdShim =
+      process.platform === "win32" &&
+      /\.(cmd|bat)$/i.test(this.config.cliPath)
+    const escapeForCmdExe = (value: string): string => {
+      const escapedForQuotes = value.replace(/"/g, '""')
+      const escapedMetaChars = escapedForQuotes.replace(
+        /([()%!^"<>&|])/g,
+        "^$1",
+      )
+      return `"${escapedMetaChars}"`
+    }
+    const proc = isWindowsCmdShim
+      ? spawn(process.env.ComSpec ?? "cmd.exe", [
+          "/d",
+          "/s",
+          "/c",
+          `${escapeForCmdExe(this.config.cliPath)} ${cliArgs
+            .map((arg) => escapeForCmdExe(arg))
+            .join(" ")}`,
+        ], {
+          cwd,
+          stdio: ["pipe", "pipe", "pipe"],
+          shell: false,
+          env: { ...process.env, TERM: "xterm-256color" },
+        })
+      : spawn(this.config.cliPath, cliArgs, {
+          cwd,
+          stdio: ["pipe", "pipe", "pipe"],
+          shell: false,
+          env: { ...process.env, TERM: "xterm-256color" },
+        })

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nbalzotti commented Apr 14, 2026

Problem

Fix

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