feat: fish shell support for venv activation instructions

src/dspy_cli/server/runner.py

@@ -221,7 +221,8 @@ def notify_cli(msg: str, level: str = "info"):
         click.echo("  2. Subclass dspy.Module")
         click.echo("  3. Are not named with a leading underscore")
         click.echo("  4. If you are using external dependencies:")
-        click.echo("     - Ensure your venv is activated")
+        from dspy_cli.utils.venv import venv_activate_command
+        click.echo(f"     - Ensure your venv is activated ({venv_activate_command()})")
         click.echo("     - Make sure you have dspy-cli as a local dependency")
         click.echo("     - Install them using pip install -e .")
 

src/dspy_cli/utils/venv.py

@@ -143,8 +143,26 @@ def validate_python_version(python: Path, min_version: tuple = (3, 9)) -> tuple[
         return False, ""
 
 
+def _is_fish_shell() -> bool:
+    """Return True when the current interactive shell is fish."""
+    if os.environ.get("FISH_VERSION"):
+        return True
+    return os.environ.get("SHELL", "").endswith("/fish")
+
+
+def venv_activate_command(venv_dir: str = ".venv") -> str:
+    """Return the shell-appropriate venv activation command."""
+    if sys.platform == "win32":
+        return f"{venv_dir}\\Scripts\\activate"
+    if _is_fish_shell():
+        return f"source {venv_dir}/bin/activate.fish"
+    return f"source {venv_dir}/bin/activate"
+
+
 def show_venv_warning():
     """Display warning and guidance when no venv is detected."""
+    activate_cmd = venv_activate_command()
+
     click.echo(click.style("⚠ Warning: No virtual environment detected", fg="yellow"))
     click.echo()
     click.echo("Running without a project venv may cause import errors if dependencies")
@@ -154,7 +172,7 @@ def show_venv_warning():
     click.echo("  1. Add dspy-cli to your project:")
     click.echo("     uv add dspy-cli")
     click.echo("  2. Create and activate a venv:")
-    click.echo("     uv sync  (or python -m venv .venv && source .venv/bin/activate)")
+    click.echo(f"     uv sync  (or python -m venv .venv && {activate_cmd})")
     click.echo("  3. Use a task runner:")
     click.echo("     uv run dspy-cli serve")
     click.echo("  4. Specify Python interpreter:")

tests/test_venv_utils.py

@@ -7,7 +7,12 @@
 from pathlib import Path
 
 
-from dspy_cli.utils.venv import sanitize_env_for_exec, validate_python_version
+from dspy_cli.utils.venv import (
+    _is_fish_shell,
+    sanitize_env_for_exec,
+    validate_python_version,
+    venv_activate_command,
+)
 
 
 class TestValidatePythonVersion:
@@ -119,3 +124,29 @@ def test_preserves_other_vars(self):
 
         # Cleanup
         os.environ.pop("MY_CUSTOM_VAR", None)
+
+
+class TestVenvActivateCommand:
+    """Tests for shell-aware activation command."""
+
+    def test_fish_via_env_var(self, monkeypatch):
+        monkeypatch.setattr(sys, "platform", "darwin")
+        monkeypatch.setenv("FISH_VERSION", "3.6.1")
+        assert _is_fish_shell()
+        assert venv_activate_command() == "source .venv/bin/activate.fish"
+
+    def test_fish_via_shell_path(self, monkeypatch):
+        monkeypatch.setattr(sys, "platform", "darwin")
+        monkeypatch.delenv("FISH_VERSION", raising=False)
+        monkeypatch.setenv("SHELL", "/usr/local/bin/fish")
+        assert _is_fish_shell()
+
+    def test_non_fish_unix(self, monkeypatch):
+        monkeypatch.setattr(sys, "platform", "darwin")
+        monkeypatch.delenv("FISH_VERSION", raising=False)
+        monkeypatch.setenv("SHELL", "/bin/bash")
+        assert venv_activate_command() == "source .venv/bin/activate"
+
+    def test_windows(self, monkeypatch):
+        monkeypatch.setattr(sys, "platform", "win32")
+        assert venv_activate_command() == r".venv\Scripts\activate"