fix(cli[load]): Only fire on_project_start when load proceeds

why: on_project_start fired before the session-exists check, so it ran
even when the user declined the reattach prompt.
what:
- Remove early on_project_start block (was before Server creation)
- Fire on_project_start inside session-exists block only after user
  confirms (_confirmed or detached)
- Fire on_project_start before new-session build path
- Add test_load_on_project_start_skipped_on_decline

Author: tony

src/tmuxp/cli/load.py

@@ -676,14 +676,6 @@ def _cleanup_debug() -> None:
     # propagate workspace inheritance (e.g. session -> window, window -> pane)
     expanded_workspace = loader.trickle(expanded_workspace)
 
-    # Run on_project_start hook — fires on every tmuxp load invocation
-    if "on_project_start" in expanded_workspace:
-        _hook_cwd = expanded_workspace.get("start_directory")
-        util.run_hook_commands(
-            expanded_workspace["on_project_start"],
-            cwd=_hook_cwd,
-        )
-
     t = Server(  # create tmux server object
         socket_name=socket_name,
         socket_path=socket_path,
@@ -716,25 +708,41 @@ def _cleanup_debug() -> None:
 
     # Session-exists check — outside spinner so prompt_yes_no is safe
     if builder.session_exists(session_name) and not append and not here:
-        # Run on_project_restart hook — fires when reattaching
-        if "on_project_restart" in expanded_workspace:
-            _hook_cwd = expanded_workspace.get("start_directory")
-            util.run_hook_commands(
-                expanded_workspace["on_project_restart"],
-                cwd=_hook_cwd,
-            )
-        if not detached and (
+        _confirmed = not detached and (
             answer_yes
             or prompt_yes_no(
                 f"{cli_colors.highlight(session_name)} is already running. Attach?",
                 default=True,
                 color_mode=cli_colors.mode,
             )
-        ):
+        )
+        if _confirmed or detached:
+            if "on_project_start" in expanded_workspace:
+                _hook_cwd = expanded_workspace.get("start_directory")
+                util.run_hook_commands(
+                    expanded_workspace["on_project_start"],
+                    cwd=_hook_cwd,
+                )
+            # Run on_project_restart hook — fires when reattaching
+            if "on_project_restart" in expanded_workspace:
+                _hook_cwd = expanded_workspace.get("start_directory")
+                util.run_hook_commands(
+                    expanded_workspace["on_project_restart"],
+                    cwd=_hook_cwd,
+                )
+        if _confirmed:
             _reattach(builder, cli_colors)
         _cleanup_debug()
         return None
 
+    # Run on_project_start hook — fires before new session build
+    if "on_project_start" in expanded_workspace:
+        _hook_cwd = expanded_workspace.get("start_directory")
+        util.run_hook_commands(
+            expanded_workspace["on_project_start"],
+            cwd=_hook_cwd,
+        )
+
     if _progress_disabled:
         _private_path = str(PrivatePath(workspace_file))
         result = _dispatch_build(

tests/cli/test_load.py

@@ -1196,6 +1196,53 @@ def test_load_on_project_restart_runs_hook(
     session.kill()
 
 
+def test_load_on_project_start_skipped_on_decline(
+    tmp_path: pathlib.Path,
+    server: Server,
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    """Tmuxp load skips on_project_start when user declines reattach."""
+    monkeypatch.delenv("TMUX", raising=False)
+
+    marker = tmp_path / "start_hook_ran"
+    workspace_file = tmp_path / "hook_start_decline.yaml"
+    workspace_file.write_text(
+        f"""\
+session_name: hook-start-decline
+on_project_start: "touch {marker}"
+windows:
+- window_name: main
+  panes:
+  - echo hello
+""",
+        encoding="utf-8",
+    )
+
+    # First load creates the session
+    session = load_workspace(
+        workspace_file,
+        socket_name=server.socket_name,
+        detached=True,
+    )
+    assert session is not None
+    assert marker.exists()
+    marker.unlink()
+
+    # Second load: session exists, user declines reattach
+    monkeypatch.setattr(
+        "tmuxp.cli.load.prompt_yes_no",
+        lambda *a, **kw: False,
+    )
+    load_workspace(
+        workspace_file,
+        socket_name=server.socket_name,
+        detached=False,
+    )
+    assert not marker.exists()
+
+    session.kill()
+
+
 class ConfigKeyPrecedenceFixture(t.NamedTuple):
     """Test fixture for config key precedence tests."""