docs: fix schedule field and add resolved_at to backup monitoring spec

docs/superpowers/specs/2026-05-11-backup-monitoring-design.md

@@ -58,7 +58,7 @@ Represents a backup job definition. Auto-created when the first report arrives.
 | `name` | string | Unique job name (e.g., "photos-daily") |
 | `source` | string | Source description (free text, e.g., "server-a:/data/photos") |
 | `target` | string | Target description (free text, e.g., "server-b:/backups/photos") |
-| `expected_schedule` | string | Cron expression or interval (e.g., "0 2 * * *") |
+| `schedule_interval_seconds` | integer | Expected interval between runs in seconds (e.g., 86400 for daily) |
 | `created_at` | datetime | When the job was first seen |
 
 ### `BackupRun`
@@ -91,6 +91,7 @@ Represents an alert condition detected for a job.
 | `severity` | enum | `warning`, `critical` |
 | `message` | string | Human-readable description |
 | `acknowledged` | boolean | Whether a user has acknowledged this alert |
+| `resolved_at` | datetime | When the alert was auto-resolved (nullable) |
 | `created_at` | datetime | When the alert was generated |
 
 ## API Specification
@@ -107,6 +108,7 @@ Submit a backup run report. Creates the job if it doesn't exist.
   "name": "photos-daily",
   "source": "server-a:/data/photos",
   "target": "server-b:/backups/photos",
+  "schedule_interval_seconds": 86400,
   "started_at": "2026-05-11T02:00:00Z",
   "ended_at": "2026-05-11T02:15:30Z",
   "status": "success",
@@ -124,6 +126,7 @@ Submit a backup run report. Creates the job if it doesn't exist.
 - `name`: required, non-empty string
 - `started_at`: required, ISO 8601 timestamp, must be in the past
 - `status`: required, one of `success`, `failure`, `in_progress`
+- `schedule_interval_seconds`: optional, if provided must be > 0. Updates the job's schedule if the job exists or is being created.
 - If `status == "success"`: `ended_at` and `duration_ms` are required
 - `bytes_transferred`: if provided, must be >= 0
 - Unknown fields in `details` are stored in `details_json`
@@ -139,6 +142,7 @@ Mark a backup job as in_progress. Useful for long-running backups.
 {
   "name": "photos-daily",
   "source": "server-a:/data/photos",
+  "schedule_interval_seconds": 86400,
   "started_at": "2026-05-11T02:00:00Z"
 }
 ```
@@ -170,7 +174,7 @@ Alerts are generated in two ways:
 | Alert Type | Trigger | Severity | Auto-Resolve |
 |------------|---------|----------|--------------|
 | `failed_status` | `status == "failure"` | `critical` | On next successful run |
-| `missed_schedule` | No run within `expected_schedule * 1.5` | `warning` | On next run arrival |
+| `missed_schedule` | No run within `schedule_interval_seconds * 1.5` | `warning` | On next run arrival |
 | `anomaly_size` | `bytes_transferred == 0` or < 10% or > 300% of 7-day median | `warning` | On next normal run |
 | `anomaly_duration` | `duration_ms` > 300% of 7-day median | `warning` | On next normal run |
 
@@ -207,10 +211,10 @@ Sortable table with columns:
 - Job name
 - Source
 - Target
-- Expected schedule
+- Schedule interval (human-readable, e.g., "Every 24 hours")
 - Last run status (color-coded chip)
 - Last run time
-- Next expected run time
+- Next expected run time (calculated from `last_run_started_at + schedule_interval_seconds`)
 
 Clicking a job row navigates to a job detail view showing historical runs.
 
@@ -261,7 +265,7 @@ Reusing existing D3 chart infrastructure:
 ## Error Handling
 
 - Invalid report data returns `422 Unprocessable Entity` with detailed validation errors
-- Duplicate reports for the same job within the same minute are idempotent (updates existing run)
+- Duplicate reports: if a run with the same `job_id` and `started_at` (within 1-second precision) already exists, the report updates the existing run instead of creating a new one
 - Malformed JSON in `details` field is accepted but stored as string in `details_json`
 - Database errors are logged and return `500 Internal Server Error`