# Reset running session start to now (issue #33)

## Problem

Sometimes a session is started but a sizeable amount of time passes before play
actually begins. The current UX to fix this is: edit the session, press "Set to
now", submit. This is three steps across two pages.

## Goal

Add a one-click button in the session list — next to the existing "Finish
session now", "Edit", and "Delete" buttons — that sets a running session's
`timestamp_start` to the current time. A confirmation dialog protects against
accidental clicks (the original start time is overwritten).

## Scope

- **Visibility:** the button shows only on running sessions (`timestamp_end is
  None`), exactly like the green "Finish session now" button.
- **Appearance:** gray button, new "reset" icon.
- **Behavior:** confirm dialog before resetting; on confirm, sets
  `timestamp_start = timezone.now()`, saves, and updates the row in place via
  htmx.

Out of scope: changing the existing Finish/Edit/Delete buttons; resetting end
time; bulk operations.

## Design

### 1. New icon — `games/templates/icons/reset.html`

A rotate/counterclockwise-arrow SVG signifying "reset". Styled like sibling
icons (`text-black dark:text-white w-4 h-4`). Icons are auto-loaded by file stem
(`common/icons.py`), so `Icon("reset")` resolves once the file exists — no
registration needed.

### 2. New view — `games/views/session.py`

Mirrors the existing `end_session` view:

```python
@login_required
def reset_session_start(request: HttpRequest, session_id: int) -> HttpResponse:
    session = get_object_or_404(Session, id=session_id)
    session.timestamp_start = timezone.now()
    session.save()
    if request.htmx:
        return HttpResponse(_session_row_fragment(session))
    return redirect("games:list_sessions")
```

`_session_row_fragment` already exists and is used by `end_session`.

### 3. New URL — `games/urls.py`

```python
path(
    "session/start/reset-to-now/from-list/<int:session_id>",
    session.reset_session_start,
    name="list_sessions_reset_session_start",
),
```

### 4. Extend `ButtonGroup` — `common/components/primitives.py`

The button-group button dict currently supports `href`, `slot`, `color`,
`title`, `hx_get`, `hx_target`. Add two optional keys threaded through both
`ButtonGroup()` and `_button_group_button()`:

- `hx_confirm` — emitted as `hx-confirm` on the `<a>`; htmx shows a native
  `confirm()` dialog before issuing the request.
- `hx_swap` — emitted as `hx-swap` on the `<a>`; needed so the returned row
  fragment replaces the row (`outerHTML`) rather than htmx's default.

Both are additive and optional; existing callers are unaffected. Update the
`ButtonGroup` docstring to list the new keys.

### 5. Button in the session list — `games/views/session.py`

Added to the `ButtonGroup` list in `list_sessions`, guarded the same way as the
Finish button:

```python
{
    "hx_get": reverse(
        "games:list_sessions_reset_session_start", args=[session.pk]
    ),
    "hx_target": f"#session-row-{session.pk}",
    "hx_swap": "outerHTML",
    "hx_confirm": "Reset this session's start time to now?",
    "slot": Icon("reset"),
    "title": "Reset start to now",
    "color": "gray",
}
if session.timestamp_end is None
else {}
```

Placement: directly after the Finish button, before Edit.

## Rationale: htmx for reset, plain href for Finish

The reset button is htmx-driven (`hx-get` + `hx-target` + `hx-swap` +
`hx-confirm`) so the confirm dialog and in-place row update come from htmx with
no inline JS — consistent with the project's "no inline JS" convention. The
existing Finish button uses a plain `href` (full-page navigation). This minor
inconsistency is left as-is to keep the change focused; the reset view still
returns a redirect for the non-htmx path, so it degrades gracefully.

## Testing

### Unit (`tests/`)

- `reset_session_start` sets `timestamp_start` to ~now and saves.
- Returns the row fragment when called via htmx; redirects to `list_sessions`
  otherwise.
- Session list renders the reset button only for running sessions
  (`timestamp_end is None`), not for finished ones.

### E2E (`e2e/`)

- On the session list with a running session, click the reset button, accept the
  confirm dialog (`page.on("dialog", lambda d: d.accept())`), and assert the
  row's displayed start time updated to ~now.

## No TypeScript build

`hx-confirm` is built into htmx; no new custom element or `.ts` file, so `make
ts` is not required for this change.