bash tool: backslash-escaped spaces make in-project paths look external (external_directory prompt / hard deny under "*": deny)

Description

The bash tool decides whether a command touches a directory outside the project by resolving the path arguments of mkdir, rm, cp, mv, touch, chmod, chown, cat, … (FILES in packages/opencode/src/tool/shell.ts). The resolution does not un-escape backslash-escaped characters in unquoted shell words, so a path spelled /tmp/my\ project/x is resolved to the literal string /tmp/my\ project/x, which is never inside the project /tmp/my project.

Consequences, all reproduced deterministically below (v1.18.29, Linux):

1. In-project paths trigger an external_directory prompt when the model escapes spaces with \ instead of quoting (mkdir -p /tmp/my\ project/sub → prompt for /tmp/my\ project/*). The same command with double quotes runs without any prompt. This also affects read-only commands in the list (cat).
2. Agents whose permission block ends in a catch-all "*": deny (a normal way to write an allowlist for subagents) get the command denied outright — there is no ask to approve — with the message The user has specified a rule which prevents you from using this specific tool call …. The escaped and the quoted spelling of the same in-project path behave differently: one is denied, the other is allowed.
3. For genuinely external paths the generated patterns/always still contain the backslashes (/tmp/other\ dir/*), so an "always allow" reply stores a pattern that will never match the same directory when it is later spelled with quotes (/tmp/other dir/*).

Local models (Qwen3.x via llama.cpp in my case) produce the \ spelling roughly half of the time, so in any project whose path contains a space this shows up constantly.

Root cause — shell.ts, argPath() → unquote() only strips a surrounding pair of quotes and leaves everything else verbatim:

function unquote(text: string) {
  if (text.length < 2) return text
  const first = text[0]
  const last = text[text.length - 1]
  if ((first === '"' || first === "'") && first === last) return text.slice(1, -1)
  return text
}

then resolvePath() → path.resolve(root, text) keeps the literal \ , containsPath(resolved, instance) is false, the directory is added to scan.dirs and ask() requests external_directory for a directory that only exists in the escaped spelling. Same code on dev today.

Suggested fix — un-escape backslash sequences of unquoted words (POSIX: outside quotes a backslash preserves the literal value of the next character):

function unquote(text: string) {
  if (text.length >= 2) {
    const first = text[0]
    const last = text[text.length - 1]
    if ((first === '"' || first === "'") && first === last) return text.slice(1, -1)
  }
  return text.replace(/\\(.)/g, "$1")
}

Partially quoted words ("/a b"/c, '/a b'/c) are the same class of problem and would need walking the tree-sitter string/raw_string/word children instead of using the concatenated text; the backslash case is the one models actually produce.

Regression test (next to does not ask for external_directory permission when rm inside project in packages/opencode/test/tool/shell.test.ts):

each("does not ask for external_directory permission for backslash-escaped in-project paths", () =>
  Effect.gen(function* () {
    const outer = yield* tmpdirScoped()
    const tmp = path.join(outer, "my project") // directory name with a space
    yield* Effect.promise(() => fs.promises.mkdir(tmp, { recursive: true }))
    yield* runIn(
      tmp,
      Effect.gen(function* () {
        const requests: Array<Omit<PermissionV1.Request, "id" | "sessionID" | "tool">> = []
        yield* run({ command: `mkdir -p ${tmp.replaceAll(" ", "\\ ")}/nested` }, capture(requests))
        expect(requests.find((r) => r.permission === "external_directory")).toBeUndefined()
      }),
    )
  }),
)

Plugins

None involved (reproduced with an empty project config apart from the fake provider below).

OpenCode version

1.18.29

Steps to reproduce

The reproduction does not need a real model: a 60-line OpenAI-compatible stub always answers with one bash tool call whose command is taken verbatim from the user prompt (CMD: …), so the exact spelling of the command is controlled. Everything else (agent, permission evaluation, bash tool) is stock OpenCode.

1. mkdir -p "/tmp/my project" && cd "/tmp/my project" and write opencode.json:

{
  "$schema": "https://opencode.ai/config.json",
  "model": "fake/fake",
  "provider": {
    "fake": {
      "npm": "@ai-sdk/openai-compatible",
      "name": "fake (repro)",
      "options": { "baseURL": "http://127.0.0.1:4098/v1", "apiKey": "x" },
      "models": { "fake": { "name": "fake", "tool_call": true, "limit": { "context": 32000, "output": 4000 } } }
    }
  },
  "agent": { "locked": { "mode": "primary", "permission": { "*": "deny", "bash": "allow", "read": "allow" } } }
}

2. Run the stub provider (below) and opencode serve --port 4097 --hostname 127.0.0.1 from that directory.
3. For each command: POST /session, then POST /session/{id}/message with {"agent":"build","model":{"providerID":"fake","modelID":"fake"},"parts":[{"type":"text","text":"CMD: <command>"}]}, poll GET /permission, reply reject, inspect the tool part / the disk.

Results (agent build, default permissions — bash: allow, external_directory: ask):

Same with agent locked ("*": deny + bash: allow):

I first hit this in a real session: three coder subagents (allowlist agents ending in "*": deny) were asked to create practice/exercise{1,2,3} inside …/Week 0/Linux COmmand Line/Less; the two that wrote Week\ 0/… were denied, the one that quoted the path succeeded.

#!/usr/bin/env python3
# OpenAI-compatible stub: if the last user message contains "CMD: <command>",
# answer with ONE `bash` tool call carrying that exact command; once a tool
# result is present in the conversation, answer the text "done".
import json, time, re
from http.server import BaseHTTPRequestHandler, HTTPServer

def sse(obj): return ("data: " + json.dumps(obj) + "\n\n").encode()
def chunk(delta, finish=None):
    return {"id": "chatcmpl-fake", "object": "chat.completion.chunk", "created": int(time.time()), "model": "fake",
            "choices": [{"index": 0, "delta": delta, "finish_reason": finish}]}

class H(BaseHTTPRequestHandler):
    def log_message(self, *a): pass
    def do_GET(self):
        b = json.dumps({"object": "list", "data": [{"id": "fake", "object": "model"}]}).encode()
        self.send_response(200); self.send_header("content-type", "application/json")
        self.send_header("content-length", str(len(b))); self.end_headers(); self.wfile.write(b)
    def do_POST(self):
        req = json.loads(self.rfile.read(int(self.headers.get("content-length", 0)) or b"{}"))
        msgs = req.get("messages", [])
        has_tool_result = any(m.get("role") == "tool" for m in msgs)
        last_user = next((m for m in reversed(msgs) if m.get("role") == "user"), {})
        content = last_user.get("content", "")
        if isinstance(content, list):
            content = " ".join(p.get("text", "") for p in content if isinstance(p, dict))
        m = re.search(r"CMD:\s*(.+)$", content, re.S)
        self.send_response(200); self.send_header("content-type", "text/event-stream"); self.end_headers()
        if m and not has_tool_result:
            args = json.dumps({"command": m.group(1).strip(), "description": "repro"})
            self.wfile.write(sse(chunk({"role": "assistant", "content": None, "tool_calls": [
                {"index": 0, "id": "call_repro", "type": "function", "function": {"name": "bash", "arguments": ""}}]})))
            self.wfile.write(sse(chunk({"tool_calls": [{"index": 0, "function": {"arguments": args}}]})))
            self.wfile.write(sse(chunk({}, "tool_calls")))
        else:
            self.wfile.write(sse(chunk({"role": "assistant", "content": "done"})))
            self.wfile.write(sse(chunk({}, "stop")))
        self.wfile.write(sse({"id": "chatcmpl-fake", "object": "chat.completion.chunk", "created": int(time.time()),
                              "model": "fake", "choices": [], "usage": {"prompt_tokens": 1, "completion_tokens": 1, "total_tokens": 2}}))
        self.wfile.write(b"data: [DONE]\n\n"); self.wfile.flush()

HTTPServer(("127.0.0.1", 4098), H).serve_forever()

Note: POST /session/{id}/shell (the TUI ! command) is not affected — it bypasses the permission scan entirely — so the reproduction has to go through a model-issued tool call.

Operating System

Arch Linux (kernel 7.2.4), x86_64

Terminal

Not relevant (reproduced through opencode serve HTTP API; originally seen in the TUI)

Start in packages/opencode/src/tool/shell.ts, tracing argPath(), unquote(), resolvePath(), and containsPath() to understand how escaped words reach permission scanning. Add the regression beside the existing external_directory test in packages/opencode/test/tool/shell.test.ts, covering an in-project path with an escaped space; done means it no longer requests external_directory.