fix(picker): keep signed-in copilot-acp visible in explicit-only desktop pickers

Two follow-up gaps found by actually running 'copilot login' end-to-end:

1. The CLI (without an OS keychain) stores its token in
   ~/.copilot/config.json under copilotTokens — a JSONC file with
   //-comment header lines. Add it as an auth-evidence source in
   _external_process_auth_evidence(), parsed comment-tolerantly and
   counting only a non-empty copilotTokens map (config.json exists after
   first launch even when logged out).

2. The desktop chat picker requests explicit_only rows, and
   _filter_explicit_provider_rows() dropped copilot-acp because a CLI
   login leaves no trace in active_provider, model.provider, or env vars
   — exactly the Anthropic-OAuth carve-out case. Keep external_process
   rows when their CLI credentials are verified (auth_verified), while
   still dropping ambient executable-on-PATH-only rows so the filter's
   narrower contract holds.

Net effect: after 'copilot login', copilot-acp appears in the desktop
picker and the Accounts card reads signed in; a machine with only the
binary installed keeps today's hidden-until-configured behavior.

hermes_cli/auth.py

@@ -7866,7 +7866,26 @@ def _external_process_auth_evidence(provider_id: str) -> tuple[bool, Optional[st
                 return True, f"env: {env_var}"
     except Exception as exc:
         logger.debug("copilot-acp env token evidence check failed: %s", exc)
-    # 2. Known on-disk GitHub Copilot credential stores (the same locations
+    # 2. The Copilot CLI's own plaintext token store (~/.copilot/config.json,
+    #    written by `copilot login` when no OS keychain is available). The file
+    #    is JSONC — strip //-comment lines before parsing.
+    try:
+        cli_config = os.path.expanduser("~/.copilot/config.json")
+        if os.path.isfile(cli_config):
+            with open(cli_config, "r", encoding="utf-8", errors="ignore") as fh:
+                raw = "\n".join(
+                    line for line in fh.read().splitlines()
+                    if not line.lstrip().startswith("//")
+                )
+            data = json.loads(raw) if raw.strip() else {}
+            tokens = data.get("copilotTokens")
+            if isinstance(tokens, dict) and any(
+                isinstance(v, str) and v.strip() for v in tokens.values()
+            ):
+                return True, "~/.copilot/config.json"
+    except Exception as exc:
+        logger.debug("copilot-acp CLI config evidence check failed: %s", exc)
+    # 3. Known on-disk GitHub Copilot credential stores (the same locations
     #    models.py already fingerprints as external credential files).
     for cred_path in (
         "~/.config/github-copilot/hosts.json",

hermes_cli/inventory.py

@@ -798,11 +798,35 @@ def _filter_explicit_provider_rows(rows: list[dict], ctx: ConfigContext) -> list
             # just accepted those same credentials when building it.
             kept.append(row)
             continue
+        if _external_process_signed_in(slug):
+            # External-process providers (copilot-acp) authenticate through
+            # their own CLI (`copilot login`), which — like the Anthropic
+            # OAuth case above — leaves no trace in active_provider,
+            # model.provider, or env vars. Verified CLI credentials are a
+            # deliberate sign-in; without this the desktop picker drops the
+            # row the picker-discovery side just accepted.
+            kept.append(row)
+            continue
         if is_provider_explicitly_configured(slug):
             kept.append(row)
     return kept
 
 
+def _external_process_signed_in(slug: str) -> bool:
+    """True when an external-process provider has verified CLI credentials."""
+    try:
+        from hermes_cli.auth import (
+            PROVIDER_REGISTRY,
+            get_external_process_provider_status,
+        )
+        pconfig = PROVIDER_REGISTRY.get(slug)
+        if not pconfig or pconfig.auth_type != "external_process":
+            return False
+        return bool(get_external_process_provider_status(slug).get("auth_verified"))
+    except Exception:
+        return False
+
+
 def _provider_is_keyless(slug: str) -> bool:
     """True when the provider's Hermes overlay declares it keyless."""
     try:

tests/hermes_cli/test_external_process_auth_status.py

@@ -120,6 +120,86 @@ def test_empty_credential_store_is_not_evidence(tmp_path, monkeypatch, _clean_co
     assert status["auth_verified"] is False
 
 
+def test_auth_verified_from_copilot_cli_plaintext_store(tmp_path, monkeypatch, _clean_copilot_env):
+    # `copilot login` without an OS keychain writes the token into
+    # ~/.copilot/config.json (JSONC, with //-comment header lines).
+    monkeypatch.setenv("HOME", str(tmp_path))
+    cfg_dir = tmp_path / ".copilot"
+    cfg_dir.mkdir()
+    (cfg_dir / "config.json").write_text(
+        "// User settings belong in settings.json.\n"
+        "// This file is managed automatically.\n"
+        "{\n"
+        '  "copilotTokens": {"https://github.com:someuser": "gho_test"},\n'
+        '  "lastLoggedInUser": {"host": "https://github.com", "login": "someuser"}\n'
+        "}\n",
+        encoding="utf-8",
+    )
+
+    status = get_external_process_provider_status("copilot-acp")
+
+    assert status["auth_verified"] is True
+    assert status["auth_source"] == "~/.copilot/config.json"
+
+
+def test_copilot_cli_store_without_tokens_is_not_evidence(tmp_path, monkeypatch, _clean_copilot_env):
+    # A config.json exists after first launch even before any login —
+    # its presence alone must not read as signed-in.
+    monkeypatch.setenv("HOME", str(tmp_path))
+    cfg_dir = tmp_path / ".copilot"
+    cfg_dir.mkdir()
+    (cfg_dir / "config.json").write_text(
+        '// managed\n{"firstLaunchAt": "2026-01-01T00:00:00Z", "copilotTokens": {}}\n',
+        encoding="utf-8",
+    )
+
+    status = get_external_process_provider_status("copilot-acp")
+
+    assert status["auth_verified"] is False
+
+
+# --- desktop picker explicit-only filter ------------------------------------
+
+
+def test_explicit_filter_keeps_signed_in_external_process_row(tmp_path, monkeypatch, _clean_copilot_env):
+    # A verified CLI login leaves no trace in active_provider/config/env —
+    # the explicit-only desktop filter must treat it like the Anthropic OAuth
+    # carve-out and keep the row.
+    from hermes_cli.inventory import _filter_explicit_provider_rows
+
+    monkeypatch.setenv("HOME", str(tmp_path))
+    cfg_dir = tmp_path / ".copilot"
+    cfg_dir.mkdir()
+    (cfg_dir / "config.json").write_text(
+        '{"copilotTokens": {"https://github.com:u": "gho_test"}}', encoding="utf-8"
+    )
+
+    class _Ctx:
+        current_provider = "nous"
+
+    rows = [{"slug": "copilot-acp", "models": ["gpt-5.4"]}]
+    kept = _filter_explicit_provider_rows(rows, _Ctx())
+
+    assert any(r["slug"] == "copilot-acp" for r in kept), \
+        "signed-in copilot-acp must survive the explicit-only picker filter"
+
+
+def test_explicit_filter_drops_unverified_external_process_row(tmp_path, monkeypatch, _clean_copilot_env):
+    # Merely having the executable on PATH is ambient discovery, not an
+    # explicit configuration — the desktop filter keeps its narrower contract.
+    from hermes_cli.inventory import _filter_explicit_provider_rows
+
+    monkeypatch.setenv("HOME", str(tmp_path))  # no credential stores
+
+    class _Ctx:
+        current_provider = "nous"
+
+    rows = [{"slug": "copilot-acp", "models": ["gpt-5.4"]}]
+    kept = _filter_explicit_provider_rows(rows, _Ctx())
+
+    assert all(r["slug"] != "copilot-acp" for r in kept)
+
+
 # --- Accounts-tab cli_command ------------------------------------------------