feat(web): export the repeaters heard in view as a 1200×1200 PNG

[khagele]

Closes #666

Builds on #724: the first commit is that PR (a Discover-heard repeater's star under its own ▲). Review the second; it rebases to one commit once #724 is in.

What

An Export button in #bar, next to Start mapping, opens a sheet with the first export of #665: Repeaters heard, the map as it stands (filters, window, hunters) as a 1200×1200 PNG, saved as mesh-hunter-repeaters-heard-YYYY-MM-DD.png. Below 640px the button moves into the menu with Start mapping and Log in (barnarrow.js, #561).

The picture shows the stars the reach layer would draw for the view, from the same registry slice, window receptions and attribution, whether the layer is on or not:

• every repeater in its own hue (assignHues), each ray's strength as a gradient within it: strong full and thick, weak lighter and thinner, with the map's width and opacity (rayStyle);
• a dot per hearing, the ▲ or ● the star hangs from, and the names that fit (most-heard first, dropped on overlap, never the ▲);
• the mapped cells (the resolution closest to 360 Mercator units, res 8 today) and the route in grey; a star whose nearest hearing is more than 30 km off is left out and named;
• a band with the mark, the title, the window as dates, up to three hunters, three numbers (repeaters, receptions, farthest) and a legend;
• always the light theme.

Decided with Kasper on mockups rendered from a real /api/points export; what was tried and not chosen (signal-tier colours, #720's hex fill over every repeater) is in docs/2026-09-27-export-repeaters-heard.md.

How

• exportheard.js: the rules (which stars, the numbers, the route, the cells, label placement, the texts), unit-tested.
• exportrender.js: a second MapLibre instance offscreen at 1200×1000 with preserveDrawingBuffer (the live map is untouched), then a canvas for the glyphs, names, scale bar and band. The bare background stands in when the hosted style does not load.
• exportsheet.js: the sheet, on the .lc-modal shell with the settings sheet's focus rules.
• Members only, like the node positions it is made of; anyone else sees the item disabled with the reason.
• hexgrid.js is copied whole from the app and added to the parity list, which web: one repeater's reach, heard and not heard, cannot be passed on as a picture #720 needs too.

Verification

• exportheard.test.js (18): what is drawn, the 30 km rule, the numbers, the route breaks, the cells, label placement, tint, window text, hunters, file name, scale bar. Five rules mutated, each caught.
• e2e/export.spec.js: a member downloads a PNG of 1200×1200 with the right name; a guest sees the reason and a disabled button; Escape closes and hands focus back. Red with the sheet unwired.
• Rendered in Chromium with the real export of 8 Aug to 7 Sep around Nijmegen: 87 repeaters, 4501 receptions.
• web: 789 tests green, eslint clean, full e2e 301 passed

🤖 Generated with Claude Code

[khagele]

Amended (6b1de2d) after a self-review:

• A star without a registry name reads as an id, as the ticker reads it (AGENTS.md §5.4 item 6): a relay hash as #db, a key as its 8-hex prefix. idLabel in exportheard.js, tested; the picture and the band use it.
• HUE_COUNT comes from coverage.js, the light style from mapcore.js (STYLES, now exported), and kmBetween is locate.js's haversineM in km.
• The halos and glyph strokes take the paper's colour (tokens.bg) instead of #ffffff.
• Closing the sheet below 900px hands the focus to the settings button, since the Export button sits in the menu that closed. The e2e test at 768px checks it.

Web: 783 tests, eslint, e2e/export.spec.js 4 passed.

[efiten]

Review of this PR's own commit (6b1de2d): two points to change, small ones below. Found by reading the code, not run.

1. A relay-hash star can be printed with a bare resolver name (change requested)
nameOf in heardExport (web/map.js:1109) falls back to cachedName(id). A rule-2 star (no candidate in reach) is keyed by its raw relay id, and RESOLVABLE (names.js:24) accepts 2-byte ids, which the points layer resolves. The picture then prints that name without ~ and without the prefixKnown check that AGENTS.md §7 rule 2 asks for. The result also depends on what the points layer resolved earlier in the session.
Proposed: for hash-kind stars use idLabel (or the name with ~, only when prefixKnown is false); keep cachedName for discover and advert keys. Plus a test with a 2-byte path_hash star and a cached name.

2. CELL_RES = 8 depends on what res 8 means (change requested)
web/exportheard.js:30. web/hexgrid.js is pinned byte-identical to app/src/hexgrid.js, and #734 changes hexSizeForRes to the server formula, where res 8 is about 8561 Mercator units instead of 360. After #734 the mapped cells become about 24× larger unless CELL_RES changes with it (res 12 is the closest to today's size). The comment's "about 600 m across" is in Mercator metres; on the ground at 52°N res 8 is about 445 m point to point.
Proposed: define the export cell by size (the res whose hexSizeForRes is closest to a target) and pin that size in a test, so a grid change turns red.

3. Small ones

• idLabel (exportheard.js:41-44): a star keyed by a nameless attributed node's full pubkey can take sender_kind path_hash from its first point and print # plus 64 hex (§5.4 item 6).
• A failed registry fetch leaves nodes = [], and the picture draws every star as an estimate with no names; the band does not say so.
• The band's off line (all off-map names joined) is not measured and runs past 1200 px with several far stars.
• web/index.html:287-289 still says "below 640px", while the item moves at 900 px.

[khagele]

Pushed 94c0bd9 for the review, rebuilt on #724 (82588a0). Per point:

1. Relay-hash star named by the resolver. heardModel takes the registry name (nameOf) and the resolver's (cachedNameOf) apart, and asks the resolver for a key only; a hash reads #id. Test: a 2-byte path_hash star with a cached name reads #db11, while a Discover key next to it takes its cached name. Red when the resolver is asked for every star.
2. CELL_RES. The export cell is now a size: CELL_SIZE 360 Mercator units, and CELL_RES is the resolution whose hexSizeForRes is closest to it (res 8 today). A test pins both, plus a factor of √2 around the size, so a grid change moves the resolution rather than the cell. With feat(app,web): ease what the map shows by zoom, on one hex system #734's formula that is res 13 (268 units, 535 point to point), not res 12 (535, 1070 point to point): 13 is the closer one. The comment and the decision log now say "about 445 m point to point at 52°N".
3. Small ones.
   • idLabel: a star reads as a hash only when its kind is a hash kind and its id is 3 bytes at most, so a nameless node's full key reads as its prefix. Tested with a path_hash first hearing.
   • A failed registry fetch adds "node list unavailable, every position estimated" to the band. Glue in map.js, not tested.
   • The "left off" line is cut with an ellipsis at the band's width (fitText, tested).
   • web/index.html says 900px.

Web: 789 tests, eslint, Playwright 301 passed. #726 and #729 are rebuilt on this one next.