feat!: incidents as the primary object

terdut-server v0.4.0 splits the alerts row into two objects, and the
endpoints this client drove for acknowledgement, comments and archiving
are gone. Pointing the same screens at the new paths would have missed
the point of the split: alerts are now Alertmanager's record, read-only
and carrying no human state, while the incident is the thing anyone
actually works on.

Incidents lead the section list and are what the client opens on. The
queue shows severity, status, assignee and age, and the detail view adds
what only exists server-side now: the group labels Alertmanager
correlated on, the member alerts, and an append-only timeline where
system events and notes are interleaved. That timeline is the whole
history the server keeps — alert rows are still mutated in place — so
rendering it in order matters more than styling it.

Actions all move onto the incident: a/A acknowledge, s assign, z/Z
snooze, c note, d delete note, x archive, R resolve.

Two of those need care rather than a keybinding:

  - R, not r, resolves, and it asks first. The server treats a manual
    resolve as terminal: a later occurrence opens a new incident instead
    of reopening this one, and an alert that never stops firing leaves
    the incident closed for good. A stray keypress is not recoverable,
    so the prompt says what it means.
  - x refuses on an open incident rather than archiving it, since
    archiving unresolved work only hides it. Snooze is offered as the
    "not now" answer, and the client treats a snoozed_until in the past
    as not snoozed, matching the server, which sweeps nothing.

Statistics lead with MTTA and MTTR, neither of which was computable
before. The server sends null until something has actually been
acknowledged or resolved, and that renders as — rather than 0: no data
is a different claim from instant.

Alerts keep a tab of their own as the raw feed — useful for asking what
Alertmanager is really sending — with an Incident column replacing Ack
By, and i in the detail view jumping to the incident where something can
be done about it. Archived now holds archived incidents; archiving an
alert is server-side housekeeping and no longer a user action.

BREAKING CHANGE: requires terdut-server v0.4.0 or later. Against an
older server every incident request 404s. Use terdut-tui v0.3.x with
servers before v0.4.0.

internal/api/client.go

@@ -63,6 +63,10 @@ func (c *Client) do(req *http.Request, out any) error {
 
 // ListAlerts fetches alerts. status may be "firing", "resolved", or "" for all.
 // Set archived=true to fetch only archived alerts; false returns only non-archived.
+//
+// Alerts are read-only on the server — there is nothing to acknowledge or
+// archive here. This is the raw feed, useful for checking what Alertmanager is
+// actually sending; the work queue is ListIncidents.
 func (c *Client) ListAlerts(status string, archived bool, limit int) ([]Alert, error) {
 	q := url.Values{}
 	if status != "" {
@@ -87,23 +91,6 @@ func (c *Client) ListAlerts(status string, archived bool, limit int) ([]Alert, e
 	return alerts, c.do(req, &alerts)
 }
 
-func (c *Client) ArchiveAlert(id int64) (*Alert, error) {
-	req, err := c.newRequest(http.MethodPost, fmt.Sprintf("/api/alerts/%d/archive", id))
-	if err != nil {
-		return nil, err
-	}
-	var alert Alert
-	return &alert, c.do(req, &alert)
-}
-
-func (c *Client) UnarchiveAlert(id int64) error {
-	req, err := c.newRequest(http.MethodDelete, fmt.Sprintf("/api/alerts/%d/archive", id))
-	if err != nil {
-		return err
-	}
-	return c.do(req, nil)
-}
-
 // GetAlertStats fetches aggregate alert counts.
 func (c *Client) GetAlertStats() (*AlertStats, error) {
 	req, err := c.newRequest(http.MethodGet, "/api/stats/alerts")
@@ -138,49 +125,172 @@ func (c *Client) GetAlert(id int64) (*Alert, error) {
 	return &alert, c.do(req, &alert)
 }
 
-func (c *Client) AcknowledgeAlert(id int64) (*Alert, error) {
-	req, err := c.newRequest(http.MethodPost, fmt.Sprintf("/api/alerts/%d/acknowledge", id))
+// ── Incidents ──────────────────────────────────────────────────────────────
+
+// ListIncidents fetches the work queue. status may be "triggered",
+// "acknowledged", "resolved", or "" for the server default of open incidents
+// only. archived and snoozed each switch the list to that set rather than
+// adding to it, matching the server's filters.
+func (c *Client) ListIncidents(status string, archived, snoozed bool, limit int) ([]Incident, error) {
+	q := url.Values{}
+	if status != "" {
+		q.Set("status", status)
+	}
+	if archived {
+		q.Set("archived", "true")
+	}
+	if snoozed {
+		q.Set("snoozed", "true")
+	}
+	if limit > 0 {
+		q.Set("limit", strconv.Itoa(limit))
+	}
+	path := "/api/incidents"
+	if len(q) > 0 {
+		path += "?" + q.Encode()
+	}
+
+	req, err := c.newRequest(http.MethodGet, path)
 	if err != nil {
 		return nil, err
 	}
-	var alert Alert
-	return &alert, c.do(req, &alert)
+	var incidents []Incident
+	return incidents, c.do(req, &incidents)
 }
 
-func (c *Client) UnacknowledgeAlert(id int64) error {
-	req, err := c.newRequest(http.MethodDelete, fmt.Sprintf("/api/alerts/%d/acknowledge", id))
+// GetIncident returns one incident with its member alerts inline.
+func (c *Client) GetIncident(id int64) (*Incident, error) {
+	req, err := c.newRequest(http.MethodGet, fmt.Sprintf("/api/incidents/%d", id))
+	if err != nil {
+		return nil, err
+	}
+	var incident Incident
+	return &incident, c.do(req, &incident)
+}
+
+func (c *Client) GetIncidentTimeline(id int64) ([]IncidentEvent, error) {
+	req, err := c.newRequest(http.MethodGet, fmt.Sprintf("/api/incidents/%d/timeline", id))
+	if err != nil {
+		return nil, err
+	}
+	var events []IncidentEvent
+	return events, c.do(req, &events)
+}
+
+func (c *Client) AcknowledgeIncident(id int64) (*Incident, error) {
+	req, err := c.newRequest(http.MethodPost, fmt.Sprintf("/api/incidents/%d/acknowledge", id))
+	if err != nil {
+		return nil, err
+	}
+	var incident Incident
+	return &incident, c.do(req, &incident)
+}
+
+func (c *Client) UnacknowledgeIncident(id int64) error {
+	req, err := c.newRequest(http.MethodDelete, fmt.Sprintf("/api/incidents/%d/acknowledge", id))
 	if err != nil {
 		return err
 	}
 	return c.do(req, nil)
 }
 
-func (c *Client) GetComments(alertID int64) ([]Comment, error) {
-	req, err := c.newRequest(http.MethodGet, fmt.Sprintf("/api/alerts/%d/comments", alertID))
+// ResolveIncident closes an incident by hand. This is terminal on the server: a
+// later occurrence in the same group opens a new incident rather than reopening
+// this one, and if the alert underneath never stops firing the incident stays
+// closed. Use SnoozeIncident for "not now".
+func (c *Client) ResolveIncident(id int64) (*Incident, error) {
+	req, err := c.newRequest(http.MethodPost, fmt.Sprintf("/api/incidents/%d/resolve", id))
 	if err != nil {
 		return nil, err
 	}
-	var comments []Comment
-	return comments, c.do(req, &comments)
+	var incident Incident
+	return &incident, c.do(req, &incident)
 }
 
-func (c *Client) AddComment(alertID int64, content string) (*Comment, error) {
-	req, err := c.newRequestWithBody(http.MethodPost, fmt.Sprintf("/api/alerts/%d/comments", alertID), map[string]string{"content": content})
+func (c *Client) AssignIncident(id, userID int64) (*Incident, error) {
+	body := struct {
+		UserID int64 `json:"user_id"`
+	}{UserID: userID}
+	req, err := c.newRequestWithBody(http.MethodPost, fmt.Sprintf("/api/incidents/%d/assign", id), body)
 	if err != nil {
 		return nil, err
 	}
-	var comment Comment
-	return &comment, c.do(req, &comment)
+	var incident Incident
+	return &incident, c.do(req, &incident)
 }
 
-func (c *Client) DeleteComment(alertID, commentID int64) error {
-	req, err := c.newRequest(http.MethodDelete, fmt.Sprintf("/api/alerts/%d/comments/%d", alertID, commentID))
+// SnoozeIncident hides an incident from the default queue for a duration,
+// without closing it.
+func (c *Client) SnoozeIncident(id int64, duration string) (*Incident, error) {
+	body := struct {
+		Duration string `json:"duration"`
+	}{Duration: duration}
+	req, err := c.newRequestWithBody(http.MethodPost, fmt.Sprintf("/api/incidents/%d/snooze", id), body)
+	if err != nil {
+		return nil, err
+	}
+	var incident Incident
+	return &incident, c.do(req, &incident)
+}
+
+func (c *Client) UnsnoozeIncident(id int64) error {
+	req, err := c.newRequest(http.MethodDelete, fmt.Sprintf("/api/incidents/%d/snooze", id))
 	if err != nil {
 		return err
 	}
 	return c.do(req, nil)
 }
 
+func (c *Client) ArchiveIncident(id int64) (*Incident, error) {
+	req, err := c.newRequest(http.MethodPost, fmt.Sprintf("/api/incidents/%d/archive", id))
+	if err != nil {
+		return nil, err
+	}
+	var incident Incident
+	return &incident, c.do(req, &incident)
+}
+
+func (c *Client) UnarchiveIncident(id int64) error {
+	req, err := c.newRequest(http.MethodDelete, fmt.Sprintf("/api/incidents/%d/archive", id))
+	if err != nil {
+		return err
+	}
+	return c.do(req, nil)
+}
+
+// AddNote appends a note to the incident's timeline.
+func (c *Client) AddNote(incidentID int64, content string) (*IncidentEvent, error) {
+	req, err := c.newRequestWithBody(http.MethodPost,
+		fmt.Sprintf("/api/incidents/%d/notes", incidentID), map[string]string{"content": content})
+	if err != nil {
+		return nil, err
+	}
+	var event IncidentEvent
+	return &event, c.do(req, &event)
+}
+
+// DeleteNote removes one of your own notes. Only notes are deletable — the rest
+// of the timeline is a record of what happened.
+func (c *Client) DeleteNote(incidentID, eventID int64) error {
+	req, err := c.newRequest(http.MethodDelete,
+		fmt.Sprintf("/api/incidents/%d/notes/%d", incidentID, eventID))
+	if err != nil {
+		return err
+	}
+	return c.do(req, nil)
+}
+
+func (c *Client) GetIncidentStats() (*IncidentStats, error) {
+	req, err := c.newRequest(http.MethodGet, "/api/stats/incidents")
+	if err != nil {
+		return nil, err
+	}
+	var stats IncidentStats
+	return &stats, c.do(req, &stats)
+}
+
+// ── Statistics ─────────────────────────────────────────────────────────────
+
 func (c *Client) GetTopAlerts(limit int) ([]TopAlert, error) {
 	req, err := c.newRequest(http.MethodGet, fmt.Sprintf("/api/stats/alerts/top?limit=%d", limit))
 	if err != nil {
@@ -232,7 +342,9 @@ func (c *Client) GetCurrentOnCall() (*ScheduleEntry, error) {
 		return nil, nil
 	}
 	if resp.StatusCode >= 400 {
-		var e struct{ Error string `json:"error"` }
+		var e struct {
+			Error string `json:"error"`
+		}
 		_ = json.NewDecoder(resp.Body).Decode(&e)
 		if e.Error != "" {
 			return nil, fmt.Errorf("server returned %d: %s", resp.StatusCode, e.Error)