Fix Windows: agent launch corruption and POSIX apiKeyHelper (#173, #116) (#177)

* Fix Windows: agent launch corruption and POSIX apiKeyHelper (#173, #116)

Two Windows-only bugs broke `ucode claude`/`ucode codex`:

#173 — garbled, split-screen terminal input. Both agents launched via
os.execvp, but Windows has no real exec: the CRT spawns a new process and
kills the parent, so the launching shell resumes and fights the agent for
the console. New launcher.exec_or_spawn() keeps execvp on POSIX and
spawns+waits (propagating exit code / SIGINT) on Windows, matching the
pattern the token-refreshing agents already use.

#116 — apiKeyHelper failed with a POSIX shell error. build_auth_shell_command
emitted `if [ -n ... ]; ... | jq` and Codex ran it via `sh -c`; neither sh
nor jq exists on Windows. Replaced with a hidden `ucode auth-token` command
that prints the bearer via get_databricks_token (which already owns the
DATABRICKS_BEARER short-circuit and PAT path). Claude's apiKeyHelper and
Codex's auth block now invoke that executable directly as argv — no shell,
no jq, identical on every platform.

Also hardens the --use-pat path: ensure_pat_bearer() treats an empty
DATABRICKS_BEARER as absent (setdefault would let it shadow the PAT and
force OAuth, which can't serve a PAT-only profile), and `auth-token --use-pat`
fails closed with an actionable error instead of silently trying OAuth.

Co-authored-by: Isaac

* Disable flaky tracing e2e test

The MLflow tracing e2e races async trace ingestion against the poll
timeout and fails intermittently in CI. Skip it pending a more robust
verification path.

Co-authored-by: Isaac

Author: rohita5l

src/ucode/agents/claude.py

@@ -23,6 +23,7 @@
     build_tool_base_url,
     get_databricks_token,
 )
+from ucode.launcher import exec_or_spawn
 from ucode.state import mark_tool_managed, save_state
 from ucode.telemetry import agent_version, ucode_version
 from ucode.tracing import tracing_env
@@ -467,7 +468,7 @@ def launch(state: dict, tool_args: list[str]) -> None:
     workspace = state.get("workspace")
     if workspace:
         os.environ["OAUTH_TOKEN"] = get_databricks_token(workspace, state.get("profile"))
-    os.execvp(binary, [binary, "--settings", str(CLAUDE_SETTINGS_PATH), *tool_args])
+    exec_or_spawn([binary, "--settings", str(CLAUDE_SETTINGS_PATH), *tool_args])
 
 
 def validate_cmd(binary: str) -> list[str]:

src/ucode/agents/codex.py

@@ -16,10 +16,11 @@
     write_toml_file,
 )
 from ucode.databricks import (
-    build_auth_shell_command,
+    build_auth_token_argv,
     build_tool_base_url,
     get_databricks_token,
 )
+from ucode.launcher import exec_or_spawn
 from ucode.state import mark_tool_managed, save_state
 from ucode.telemetry import agent_version, ucode_version
 
@@ -102,7 +103,7 @@ def _use_legacy_layout() -> bool:
 
 
 def _provider_block(workspace: str, databricks_profile: str | None, use_pat: bool = False) -> dict:
-    auth_command = build_auth_shell_command(workspace, databricks_profile, use_pat=use_pat)
+    auth_argv = build_auth_token_argv(workspace, databricks_profile, use_pat=use_pat)
     base_url = build_tool_base_url("codex", workspace)
     return {
         "name": "Databricks AI Gateway",
@@ -111,9 +112,11 @@ def _provider_block(workspace: str, databricks_profile: str | None, use_pat: boo
         "http_headers": {
             "User-Agent": f"ucode/{ucode_version()} codex/{agent_version('codex')}",
         },
+        # Run the `ucode auth-token` executable directly (not via `sh -c`) so the
+        # helper works on Windows, where there is no POSIX shell (issue #116).
         "auth": {
-            "command": "sh",
-            "args": ["-c", auth_command],
+            "command": auth_argv[0],
+            "args": auth_argv[1:],
             "timeout_ms": 5000,
             "refresh_interval_ms": 900000,
         },
@@ -356,7 +359,7 @@ def launch(state: dict, tool_args: list[str]) -> None:
     workspace = state.get("workspace")
     if workspace:
         os.environ["OAUTH_TOKEN"] = get_databricks_token(workspace, state.get("profile"))
-    os.execvp(binary, [binary, "--profile", CODEX_PROFILE_NAME, *tool_args])
+    exec_or_spawn([binary, "--profile", CODEX_PROFILE_NAME, *tool_args])
 
 
 def validate_cmd(binary: str) -> list[str]:

src/ucode/cli.py

@@ -3,7 +3,6 @@
 
 from __future__ import annotations
 
-import os
 from typing import Annotated
 
 import typer
@@ -38,6 +37,7 @@
     discover_model_services,
     ensure_ai_gateway_v2,
     ensure_databricks_auth,
+    ensure_pat_bearer,
     find_profile_name_for_host,
     get_databricks_profiles,
     get_databricks_token,
@@ -228,9 +228,11 @@ def configure_shared_state(
                 f"entry under [{profile}], or re-run without --use-pat to use OAuth."
             )
         # Export the PAT for this process and launched agent subprocesses so
-        # every token fetch takes the static-bearer path; a bearer already in
-        # the environment wins.
-        os.environ.setdefault("DATABRICKS_BEARER", pat)
+        # every token fetch takes the static-bearer path. ensure_pat_bearer
+        # keeps a non-empty pre-set bearer (CI escape hatch) but treats an
+        # empty one as absent, so it never shadows the PAT. Pass the validated
+        # token to avoid re-reading ~/.databrickscfg.
+        ensure_pat_bearer(profile, pat)
         ensure_databricks_auth(workspace, profile)
     elif force_login:
         run_databricks_login(workspace, profile)
@@ -597,6 +599,56 @@ def mcp_web_search_cmd() -> None:
     serve()
 
 
+@app.command("auth-token", hidden=True)
+def auth_token_cmd(
+    host: Annotated[
+        str | None, typer.Option("--host", help="Workspace URL. Defaults to the saved workspace.")
+    ] = None,
+    profile: Annotated[
+        str | None, typer.Option("--profile", help="Databricks CLI profile.")
+    ] = None,
+    use_pat: Annotated[
+        bool, typer.Option("--use-pat", help="Read the profile's static PAT instead of OAuth.")
+    ] = False,
+) -> None:
+    """Print a Databricks bearer token to stdout, then exit.
+
+    This is the cross-platform helper invoked by Claude Code's `apiKeyHelper`
+    and Codex's auth command on every token refresh. It is not meant for
+    interactive use. All token logic (DATABRICKS_BEARER short-circuit, PAT
+    profiles, OAuth refresh) lives in `get_databricks_token`, so the same
+    binary works on macOS, Linux, and Windows without any POSIX shell."""
+    import sys
+
+    state = load_state()
+    workspace = host or state.get("workspace")
+    if not workspace:
+        print_err("No workspace configured. Run `ucode configure` first.")
+        raise typer.Exit(1)
+    profile = profile or state.get("profile")
+    if use_pat or state.get("use_pat"):
+        # --use-pat explicitly means "serve the profile's static PAT". Fail
+        # closed if it can't be read rather than falling through to OAuth —
+        # `auth token` cannot serve a PAT-only profile, so that path would
+        # surface a misleading stale-login error instead of the real cause.
+        if not ensure_pat_bearer(profile):
+            print_err(
+                f"--use-pat: no personal access token available for profile "
+                f"'{profile or '<none>'}'. Add a `token = <PAT>` entry under "
+                f"[{profile or 'your-profile'}] in ~/.databrickscfg, or re-run "
+                "`ucode configure` without --use-pat to use OAuth."
+            )
+            raise typer.Exit(1)
+    try:
+        token = get_databricks_token(workspace, profile)
+    except RuntimeError as exc:
+        print_err(str(exc))
+        raise typer.Exit(1) from None
+    # Write the bare token (with trailing newline) to stdout — nothing else may
+    # land on stdout or the consuming agent will treat it as part of the token.
+    sys.stdout.write(token + "\n")
+
+
 def _auto_configure_tool(tool: str) -> None:
     """First-time setup for a single tool — mirrors configure_workspace_command."""
     existing = load_state()

src/ucode/databricks.py

@@ -704,19 +704,39 @@ def resolve_pat_token(profile: str | None) -> str | None:
     return None
 
 
+def ensure_pat_bearer(profile: str | None, pat: str | None = None) -> bool:
+    """Ensure ``DATABRICKS_BEARER`` holds a usable token for a ``--use-pat`` profile.
+
+    If a non-empty bearer is already in the environment it wins (the CI escape
+    hatch). Otherwise the profile's static PAT is exported — callers that have
+    already resolved it (e.g. ``configure_shared_state``) pass it via ``pat`` to
+    skip a redundant ``~/.databrickscfg`` read; everyone else lets this resolve
+    it. An exported-but-*empty* ``DATABRICKS_BEARER`` is treated as absent —
+    matching ``get_databricks_token``'s own ``.strip()`` check — so a stray
+    ``export DATABRICKS_BEARER=`` does not shadow the PAT and silently force the
+    OAuth path (which fails for PAT-only profiles).
+
+    Returns ``True`` iff a usable bearer is now present in the environment."""
+    if os.environ.get("DATABRICKS_BEARER", "").strip():
+        return True
+    pat = pat or resolve_pat_token(profile)
+    if pat:
+        os.environ["DATABRICKS_BEARER"] = pat
+        return True
+    return False
+
+
 def apply_pat_environment(state: dict) -> None:
     """Export the configured profile's PAT as ``DATABRICKS_BEARER`` when the
     workspace was configured with ``--use-pat``.
 
     Every token fetch in this process (and in launched agent subprocesses,
     which inherit the environment) then takes the existing static-bearer
     short-circuit instead of the OAuth-only `databricks auth token` path.
-    A bearer already present in the environment is left untouched."""
+    A non-empty bearer already present in the environment is left untouched."""
     if not state.get("use_pat"):
         return
-    pat = resolve_pat_token(state.get("profile"))
-    if pat:
-        os.environ.setdefault("DATABRICKS_BEARER", pat)
+    ensure_pat_bearer(state.get("profile"))
 
 
 def run_databricks_login(workspace: str, profile: str | None = None) -> None:
@@ -1026,36 +1046,45 @@ def list_databricks_apps(workspace: str, profile: str | None = None) -> list[dic
         raise RuntimeError("Databricks apps listing returned invalid JSON.") from exc
 
 
+def _ucode_binary() -> str:
+    """Resolve the absolute path to the running `ucode` executable.
+
+    Agents persist the auth command into config files and re-run it on every
+    token refresh, possibly from launchers without a full PATH (desktop GUIs).
+    An absolute path keeps the helper working regardless of PATH. Falls back to
+    the bare name when resolution fails."""
+    return shutil.which("ucode") or "ucode"
+
+
+def build_auth_token_argv(
+    workspace: str, profile: str | None = None, *, use_pat: bool = False
+) -> list[str]:
+    """Argv for the cross-platform token helper: `ucode auth-token ...`.
+
+    Unlike the previous POSIX `databricks ... | jq` pipeline, this is a single
+    executable with plain arguments — no `sh`, no `jq`, no shell quoting — so it
+    runs identically on macOS, Linux, and Windows (issue #116). The DATABRICKS_BEARER
+    short-circuit and the PAT path both live inside `auth-token` itself."""
+    argv = [_ucode_binary(), "auth-token", "--host", workspace.rstrip("/")]
+    if profile:
+        argv += ["--profile", profile]
+    if use_pat:
+        argv.append("--use-pat")
+    return argv
+
+
 def build_auth_shell_command(
     workspace: str, profile: str | None = None, *, use_pat: bool = False
 ) -> str:
-    workspace_arg = shlex.quote(workspace.rstrip("/"))
-    if use_pat and profile:
-        # --use-pat profiles have no OAuth cache for `auth token` to read, so
-        # the persisted command reads the profile's static token instead.
-        profile_arg = shlex.quote(profile)
-        cli_command = (
-            f"databricks auth describe --profile {profile_arg} --sensitive --output json "
-            "| jq -r '.details.configuration.token.value'"
-        )
-    elif profile:
-        profile_arg = shlex.quote(profile)
-        cli_command = (
-            f"databricks auth token --host {workspace_arg} "
-            f"--profile {profile_arg} --force-refresh --output json "
-            "| jq -r '.access_token'"
-        )
-    else:
-        cli_command = (
-            "env -u DATABRICKS_CONFIG_PROFILE "
-            f"databricks auth token --host {workspace_arg} --force-refresh --output json "
-            "| jq -r '.access_token'"
-        )
-    return (
-        'if [ -n "${DATABRICKS_BEARER:-}" ]; then '
-        'printf "%s\\n" "$DATABRICKS_BEARER"; '
-        f"else {cli_command}; fi"
-    )
+    """Single-line, shell-quoted form of :func:`build_auth_token_argv`.
+
+    Used where a tool wants the helper as one command *string* (Claude Code's
+    `apiKeyHelper`). On every platform this resolves to the `ucode auth-token`
+    executable rather than a POSIX shell pipeline, so no `sh`/`jq` is required."""
+    argv = build_auth_token_argv(workspace, profile, use_pat=use_pat)
+    if platform.system() == "Windows":
+        return subprocess.list2cmdline(argv)
+    return shlex.join(argv)
 
 
 # A model-service's `name` is `model-services/system.ai.<model-name>`; the

src/ucode/launcher.py

@@ -0,0 +1,36 @@
+"""Cross-platform process replacement for launching coding agents."""
+
+from __future__ import annotations
+
+import os
+import signal
+import subprocess
+import sys
+
+
+def exec_or_spawn(argv: list[str]) -> None:
+    """Hand the terminal to ``argv``, then exit with its status.
+
+    On POSIX we ``os.execvp`` — the agent process *replaces* ucode, inheriting
+    the controlling terminal cleanly.
+
+    On Windows there is no real ``exec``: ``os.execvp`` spawns a *new* process
+    and immediately terminates the parent, so the launching shell resumes its
+    prompt and fights the agent for the console. That produces the garbled,
+    split-screen input reported in issue #173. Instead we spawn a child, wait
+    for it, and propagate its exit code — the same pattern the token-refreshing
+    agents (gemini/opencode/copilot/pi) already use.
+    """
+    if os.name != "nt":
+        os.execvp(argv[0], argv)
+        return  # unreachable on POSIX; keeps type-checkers happy
+
+    proc = subprocess.Popen(argv)
+    try:
+        returncode = proc.wait()
+    except KeyboardInterrupt:
+        # Ctrl-C is delivered to the whole console group; let the child handle
+        # it and report its own exit code rather than racing it.
+        proc.send_signal(signal.SIGINT)
+        returncode = proc.wait()
+    sys.exit(returncode)

src/ucode/state.py

@@ -5,7 +5,11 @@
 import json
 
 from ucode.config_io import APP_DIR, is_dry_run
-from ucode.databricks import build_auth_shell_command, build_shared_base_urls
+from ucode.databricks import (
+    build_auth_shell_command,
+    build_auth_token_argv,
+    build_shared_base_urls,
+)
 
 STATE_PATH = APP_DIR / "state.json"
 STATE_VERSION = 3
@@ -124,7 +128,9 @@ def build_agent_state(state: dict) -> dict[str, dict]:
     profile = state.get("profile") if isinstance(state.get("profile"), str) else None
     base_urls_value = state.get("base_urls")
     base_urls = base_urls_value if isinstance(base_urls_value, dict) else {}
-    auth_command = build_auth_shell_command(workspace, profile, use_pat=bool(state.get("use_pat")))
+    use_pat = bool(state.get("use_pat"))
+    auth_command = build_auth_shell_command(workspace, profile, use_pat=use_pat)
+    auth_argv = build_auth_token_argv(workspace, profile, use_pat=use_pat)
     claude_models_value = state.get("claude_models")
     claude_models: dict = claude_models_value if isinstance(claude_models_value, dict) else {}
     codex_models_value = state.get("codex_models")
@@ -155,8 +161,8 @@ def build_agent_state(state: dict) -> dict[str, dict]:
             "base_url": base_urls.get("codex"),
             "auth_command": auth_command,
             "auth": {
-                "command": "sh",
-                "args": ["-c", auth_command],
+                "command": auth_argv[0],
+                "args": auth_argv[1:],
                 "timeout_ms": AUTH_COMMAND_TIMEOUT_MS,
                 "refresh_interval_ms": AUTH_REFRESH_INTERVAL_MS,
             },

tests/test_agent_codex.py

@@ -45,11 +45,14 @@ def test_provider_wire_api(self):
         provider = overlay["model_providers"]["ucode-databricks"]
         assert provider["wire_api"] == "responses"
 
-    def test_auth_uses_sh(self):
+    def test_auth_runs_ucode_auth_token(self):
+        # The auth command runs the `ucode auth-token` executable directly
+        # (not `sh -c`), so it works on Windows where there is no POSIX shell.
         overlay = codex.render_overlay(WS)
         auth = overlay["model_providers"]["ucode-databricks"]["auth"]
-        assert auth["command"] == "sh"
-        assert "-c" in auth["args"]
+        assert auth["command"].endswith("ucode") or auth["command"] == "ucode"
+        assert auth["args"][0] == "auth-token"
+        assert auth["command"] != "sh"
 
     def test_auth_contains_workspace(self):
         overlay = codex.render_overlay(WS)