Sightings: a Reader report defers a Poll of a solitary Series (#103) (#108)

Closes #103.

A userscript PUT already carries the Latest Chapter the Reader's own browser read off the Series page. It may now stand in for a Poll, under one restriction and one ceiling:

- **Solitary Series only** — a Series two Readers share is Polled on schedule however recently it was sighted, so one Reader's mistake can never reach another's list.
- **One rest of standing**, and a **six-rest ceiling** (`sightingCeilingRests`, counted in the Site's own Rest): however many Sightings arrive, an unpolled Series is Polled.

Both live in the due query's HAVING clause (`Store.DueForLatestCheck`) — the same place the schedule has always been decided, so no timer and no second code path can disagree with it. No new query per scheduler round.

Judgement costs no extra request. `Poller.checkOne` already compares what the Site publishes against what is stored: a lower number contradicts the Sighting (Reader and both numbers logged), the same number confirms it, a higher number is the Site publishing and clears the attribution instead. Three contradictions stop that Reader deferring — their reports still write the Latest Chapter — and twenty consecutive confirmations forgive them, as does the owner's clear-marks control from #102.

One client change was required: both userscripts skipped the PUT when the number had not moved, so the case the whole mechanism exists for — visiting a Series with nothing new — never reached the backend. `reportLatestChapter` sends it, skipping only the local write and the re-render. A numberless PUT (favourite toggle, progress from a chapter page) is no Sighting and defers nothing.

Schema: migration `0011_series_sightings.sql` adds `series.latest_sighted_at` and `series.latest_raised_by`. Trust model, thresholds, and rejected alternatives with their citations: `docs/adr/0011-sighting-deferral-trust-model.md`.

Reviewed on both axes (spec against #103, standards against the repo's rules); the blocker — attribution surviving a Poll that overtook the report — is fixed and has a test that fails without the fix.

Verification: `go test ./...` green (needs Docker), `node --test userscript/test/*.test.js` 66 pass.
Reviewed-on: #108
Co-authored-by: Sulthan Zaki <sultankiki05@gmail.com>
Co-committed-by: Sulthan Zaki <sultankiki05@gmail.com>

backend/AGENTS.md

@@ -27,7 +27,8 @@ Guidance for OpenCode (and Claude Code) working under `backend/`. See root `AGEN
   `series` keyed `(site, series_id)`
   (`asura`|`demonic`|`comix`|`kagane`|`novelfull`|`lightnovelworld`) owns the
   shared facts — title, cover, canonical URL, `kind` (`manga`|`novel`),
-  Latest Chapter, `latest_checked_at` — and `bookmarks` holds only what
+  Latest Chapter, `latest_checked_at`, and the Sighting pair
+  `latest_sighted_at`/`latest_raised_by` (issue #103) — and `bookmarks` holds only what
   differs between readers: progress, favourite, lifecycle bucket,
   `updated_at`. A bookmark is keyed `(reader_id, site, series_id)` — no
   surrogate id; the wire `key` is derived as `site:series_id` on read — and
@@ -78,7 +79,9 @@ Guidance for OpenCode (and Claude Code) working under `backend/`. See root `AGEN
   each re-checking that Site's bookmarked series' newest published chapter from
   backend's own network access, so `latest_chapter` stays fresh when the user
   isn't browsing. Second, parallel signal — the userscript keeps its own
-  `maybeCaptureLatestOnSeriesPage`/`backgroundRefreshLatest` logic unchanged.
+  `maybeCaptureLatestOnSeriesPage`/`backgroundRefreshLatest` schedule, and its
+  `reportLatestChapter` PUTs every read, unchanged numbers included, because an
+  unchanged read is exactly the Sighting worth deferring a Poll on (#103).
   Two independent clocks: per-series rest (`series.latest_checked_at`,
   enforced by `Store.DueForLatestCheck`'s WHERE clause — `now - Rest`) and
   per-Lane gap (the Lane sleeping between fetches, `effectiveGap`). Both live
@@ -91,6 +94,29 @@ Guidance for OpenCode (and Claude Code) working under `backend/`. See root `AGEN
   every tick; found chapter written straight to the series row via
   `Store.SetLatestChapter`, so a bookmark's `updated_at` — and the list
   order — is never touched.
+  **Sightings** (issue #103, ADR-0011) let a Reader's own page read defer a
+  Poll: `Store.RecordSighting` — called by the PUT handler *before* the Upsert,
+  because the raise test needs the row as it stands — stamps
+  `series.latest_sighted_at` and, when the report raises the stored number,
+  names its Reader in `series.latest_raised_by`. The due query's HAVING clause
+  is where deferral lives: a Series is skipped only while it has exactly one
+  Bookmark, was sighted within one Rest, and is under the ceiling
+  (`sightingCeilingRests`, six of that Site's rests) since its last Poll. So a
+  shared Series is never deferred, and no Series goes six hours unpolled
+  whatever arrives. `checkOne` judges the named Reader off the comparison it
+  already makes: a lower number is a contradiction (logged with the Reader and
+  both numbers), the same number an agreement, a higher number the Site
+  publishing and neither — that last one clears the attribution instead, since
+  the value the Poll then stores is its own and a later retraction is not the
+  Reader's fault. Three contradictions
+  (`store.SightingDisagreementLimit`) stop that Reader deferring — their
+  reports still write the Latest Chapter — and twenty consecutive agreements
+  (`store.SightingAgreementsToClear`) forgive them, as does the owner's
+  clear-marks control. Deferral is recomputed from live facts every round, so
+  nothing needs invalidating when a Series gains a second Bookmark; the one
+  input read earlier is the Reader's marks, checked when the Sighting is
+  recorded, so crossing the threshold or being cleared takes effect from that
+  Reader's next Sighting and the standing already bought lasts out its rest.
   Refusals and browser loss are Lane-local: two `errChallengeHeld` in one pass
   stop that Site for `refuseBackoff` (15m) while other Lanes continue; an
   `errBrowserInterrupted` (remote Chrome restart) sets a shared Poller flag