224 lines
8.0 KiB
Markdown
224 lines
8.0 KiB
Markdown
# P6-03 — Repo size trend graphs
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Sparkline on the dashboard host row + full chart on the host repo
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page, both showing repo growth over time. Closes the last
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operator-visibility gap in Phase 6 alongside Prometheus metrics
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(P6-04).
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## Goals
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- Operators can see at a glance whether a host's repo is growing,
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stable, or shrinking, without leaving the dashboard.
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- A second screen on the repo page exposes the same data over a
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longer window with a snapshot-count overlay so retention
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behaviour can be eyeballed against size.
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- Zero new client-side dependencies; matches the existing
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HTMX + server-rendered idiom used everywhere else in the UI.
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## Non-goals
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- No backfill of historical data. Trend lights up with whatever
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the agents report from the day this ships.
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- No per-source-group breakdown — repo-level only.
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- No alerting on growth rate (dedicated to a future ticket if a
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user asks).
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- No JSON API surface. Prometheus exposure is P6-04, separate.
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## Decisions taken in brainstorming
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- **Metrics:** `total_size_bytes` (sparkline + chart) and
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`snapshot_count` (chart only). Raw size dropped as redundant.
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- **Cadence:** one row per `(host_id, UTC date)`, last-write-wins
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per column. Bounded at ~365 rows/host/year regardless of job
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frequency.
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- **Backfill:** none. Pure forward-fill from launch day.
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- **Rendering:** server-rendered inline SVG, no JS library.
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- **Spans:** sparkline fixed at 30 days; chart has `30d | 90d | 1y`
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range selector, server-rendered swap.
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## Schema
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New migration `internal/store/migrations/0023_host_repo_stats_history.sql`:
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```sql
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CREATE TABLE host_repo_stats_history (
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host_id TEXT NOT NULL REFERENCES hosts(id) ON DELETE CASCADE,
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day TEXT NOT NULL, -- 'YYYY-MM-DD' UTC
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total_size_bytes INTEGER, -- nullable; partial patches don't overwrite
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snapshot_count INTEGER, -- nullable
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recorded_at TEXT NOT NULL, -- RFC3339Nano of last write touching this row
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PRIMARY KEY (host_id, day)
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);
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CREATE INDEX host_repo_stats_history_host_day
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ON host_repo_stats_history(host_id, day DESC);
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```
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FK cascade matches every other host-scoped table; deleting a host
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through `Store.DeleteHost` (NS-01) wipes its history automatically.
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## Write path
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Hook the existing `MsgRepoStats` handler in
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`internal/server/ws/handler.go` (around line 319). After the
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existing `UpsertHostRepoStats(ctx, hostID, patch)` call, append:
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```go
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day := time.Now().UTC().Format("2006-01-02")
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if err := deps.Store.UpsertHostRepoStatsHistory(ctx, hostID, day, patch); err != nil {
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slog.Warn("ws: upsert host repo stats history", "host_id", hostID, "err", err)
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}
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```
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A history-write failure is logged and dropped — never blocks the
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main upsert. The partial-update contract that
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`UpsertHostRepoStats` already implements is preserved at the
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history layer:
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```sql
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INSERT INTO host_repo_stats_history (host_id, day, total_size_bytes, snapshot_count, recorded_at)
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VALUES (?, ?, ?, ?, ?)
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ON CONFLICT(host_id, day) DO UPDATE SET
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total_size_bytes = COALESCE(excluded.total_size_bytes, host_repo_stats_history.total_size_bytes),
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snapshot_count = COALESCE(excluded.snapshot_count, host_repo_stats_history.snapshot_count),
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recorded_at = excluded.recorded_at;
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```
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This is critical: the agent's prune handler in
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`internal/agent/runner/runner.go:318` emits a stats patch that
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only carries `LastPruneAt`. Without `COALESCE`, that prune ack
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would null out a `total_size_bytes` we'd already captured from a
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backup earlier the same day.
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## Read path
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Two new helpers in `internal/store/host_repo_stats_history.go`:
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```go
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type RepoStatsHistoryPoint struct {
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Day time.Time // 00:00:00 UTC
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TotalSizeBytes *int64
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SnapshotCount *int64
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}
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func (s *Store) ListHostRepoStatsHistory(
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ctx context.Context, hostID string, since time.Time,
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) ([]RepoStatsHistoryPoint, error)
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```
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Returns rows ordered by `day` ascending where at least one metric
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is non-null. The renderer connects available points with a
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straight line — there is no explicit gap representation. A host
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that was offline for a week shows a single segment spanning the
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gap, which is the right visual: the repo state didn't change.
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## Rendering
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New package `internal/web/sparkline`. Pure Go, no template
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dependency:
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```go
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type Series struct {
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Name string
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Points []float64 // nil-points represented as math.NaN
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Stroke string // CSS color
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}
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func RenderSparkline(points []float64, width, height int) template.HTML
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func RenderChart(series []Series, days []time.Time, opts ChartOpts) template.HTML
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```
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`RenderChart` produces a 600×220 SVG with:
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- Light horizontal gridlines (4 bands).
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- Two y-axes: bytes (left, blue) and count (right, amber). Each
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series is normalised against its own axis.
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- X-axis labels at start, midpoint, and end of the window.
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- Per-point `<circle>` with a `<title>` for hover tooltips —
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accessible by default, no JS.
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- Empty state: faint dashed baseline + centered "no data yet"
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text.
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Sparkline is 80×20, single blue polyline, single `<title>` on the
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group element showing `"current → 30d ago"`.
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Two new partials:
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- `web/templates/partials/repo_size_sparkline.html`
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- `web/templates/partials/repo_size_chart.html`
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Both call into the renderer with the appropriate opts. No
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inline `<style>` — colours come from existing Tailwind palette
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classes already used elsewhere (`text-blue-500`, `text-amber-500`).
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## UI placement
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### Dashboard host row
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`web/templates/partials/host_row.html` gains one `<td>` between
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the existing "Repo size" cell and "Snapshots" cell. Width ≈ 88px.
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Cell renders the sparkline partial; if `len(points) < 2` the cell
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shows "—" centred (matches the existing no-data idiom for
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last-backup time in the same partial).
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The dashboard's existing 5-second htmx live-refresh
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(`hx-trigger="every 5s ..."` from NS-04) re-renders this cell
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along with the rest of the row. No extra polling.
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### Host repo page
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`web/templates/pages/host_repo.html` gains a "Trend" panel
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inserted between the existing summary panel and the maintenance
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panel. Panel contains:
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- Range pills `30d | 90d | 1y` (anchor links with
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`hx-get="/hosts/{id}/repo/trend?range=…"` and
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`hx-target="#repo-trend-chart" hx-swap="outerHTML"`).
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- The chart partial wrapped in `<div id="repo-trend-chart">`.
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- A small legend strip below the chart.
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## Endpoints
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- `GET /hosts/{id}/repo/trend?range=30d|90d|1y` — admin/operator,
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htmx fragment, returns the chart partial. Auth reuses the
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existing host-scoped middleware on the `/hosts/{id}` family.
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Invalid `range` falls back to 30d.
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No new admin-only surface — anyone with read access to the host
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can see the trend.
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## Testing
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- `internal/store/host_repo_stats_history_test.go` — upsert
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merges partial patches without nulling; ordering; since-day
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filter; cascade on host delete.
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- `internal/web/sparkline/sparkline_test.go` — golden SVG files
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for: empty input, single point, full 30-day series, mixed
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null points. Goldens live under `testdata/`.
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- `internal/server/http/ui_repo_test.go` — trend panel renders
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with seeded history; range selector swaps server-side; empty
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state.
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- `internal/server/http/ui_dashboard_test.go` — host row sparkline
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cell present and renders SVG when points exist, "—" when not.
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- Smoke after build: dashboard row shows sparkline once two days
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of data exist; repo page chart toggles cleanly between ranges.
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## Migration / rollout
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- Schema migration is additive — no risk to existing tables.
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- Write path is best-effort; on schema issue the main repo-stats
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upsert is unaffected.
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- No agent change required, so no fleet update needed.
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## Acceptance
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- After two days of operation, the dashboard sparkline shows a
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visible line for any host that has run a backup or
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maintenance op on both days.
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- Host repo page renders the trend panel with the snapshot-count
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overlay; range selector switches view without a full page
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reload.
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- `go test ./...` and `go vet ./...` clean.
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- Smoke env exercise: backup → sparkline updates; range pills
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swap; FK cascade verified by deleting a host and checking the
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history table.
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