Calendar: era colours that blend, era look settings, and era info for players

[keyxmakerx]

Requested by Key Maker · project thread

Fixes #923
Security implication:

• New visibility rule. Players and Scribes now receive eras that are not hidden. Before this change they received none.
• Hidden eras. An era marked "hidden until it begins" is removed on the server from every player-facing read until the calendar's current date reaches it: its name, colours, description and events. While it is hidden, the previous era carries on for players.
• DM note. A Director's note on an era is never sent to players.
• Paths checked:
  • the calendar page's inline data
  • GET /calendars/:calid and the public route
  • the Calendars list and peek
  • the skybox and widget blocks
  • the syncapi /calendar/eras and /calendar routes
  • event reads: month, single, by-ids, upcoming, timeline, search, the AI export's Safe mode and repeat-rule anchors
• New endpoint GET /calendars/:calid/eras/:eraID/events.
  • The era must belong to the calendar, and the calendar to the campaign.
  • A hidden era answers the same 404 as a missing one.
  • Events go through the same per-event filters as other reads, capped at 500.
• Lore page. The page's name is joined only within the campaign and blanked when the viewer can't see that page.
• Writes.
  • Era create, update and delete need CanAuthorDmOnly; PUT /era-look needs Owner.
  • Era ids are scoped to the calendar.
  • Imports drop lore_entity_id.

Consumer-verified: n/a (the new endpoint's only consumer is calendar_view.js in this PR)
Mockup: "Era blend" v3 look and v4 settings and info (approved, with option B), https://claude.ai/artifact/1YXz5K4GiPEV6NkytF8uo1. Placement changes per Key Maker's note are on the Sign-offs card "Calendar eras: where the info and the look settings ended up".

What this changes

Before: an era was a name and one colour, which players never saw. The calendar showed nothing where one era turned into the next.

After:

• The blend. A faint tint of each era's colours sits behind the days, with a soft, slow curl of colour only where two eras meet. It eases to a stop when the viewer steps away, uses a lighter version on weak devices, and becomes a still tint under reduced motion.
• Era info. Pointing at the era name above the month shows its dates. Clicking it slides open a panel under the month header with:
  • a timeline of every era (click one to jump there)
  • the era's dates, length and description
  • its key events (the events marked major)
  • a lore page link
  • a Director-only note
• Era look settings. An Era look section on the calendar settings page sets:
  • colours on or off
  • Still / Slow and subtle / Lively, plus intensity and speed
  • each era's two colours, Gas or Ink style, and its own feel
• Per-era fields. Each era can be hidden from players until it begins.

How:

• Migration 024_era_look (plugin, idempotent, with a down file) adds:
  • four calendar-wide columns
  • six per-era columns, including the lore entity FK with ON DELETE SET NULL
• Painter. calendar_era_blend.js is a canvas painter shared by the calendar and the settings preview.
• View. calendar_view.js adds the chips, tooltip and inline panel.
• Settings. calendar_era_look.templ, era_look_view.go and calendar_era_look.js make up the settings section. The per-era hidden flag, note and lore page are in the era form (Eras button in Edit).
• Export and import round-trip the new fields.
• Partial updates: absent preserves, null clears, except that the calendar-wide look is saved whole (its only writers always send all four values).

Deviations from the mockup:

• Era info placement. As Key Maker asked, it expands from the era name instead of sitting on the page.
• Settings preview. The settings live on the settings page with their own Save and Cancel, without the side-by-side live preview.
• "Begins" label. It is a plain label, not a button, to avoid nested buttons; keyboard users use the chip.
• Lore link. It can only point to a campaign page.
• Era lengths. On calendars with uneven months they are approximate.

Why

#923, from Key Maker's Sign-offs answers on the era blend cards: "i hate this to be just a visual thing", "i'd want my slow and subtle", and "it needs to be something that expands, or hover overs".

Test plan

• templ generate (v0.3.1001): no changes. go build ./... OK.
• go test ./... -short -count=1: 50 packages ok.
• CHRONICLE_TEST_DB_DSN=... go test ./internal/plugins/calendar/... -count=1: ok, 323 tests. This includes the migration apply-twice and roll-back-twice test, the era repository test and the export round-trip.
• node --test test/js/*.test.mjs: 323/323, including the new calendar_era_blend.test.mjs (13).
• golangci-lint run ./...: 0 issues. All 9 tools/check-*.sh pass.
• Live Playwright run against a real server and a fresh DB: 85/85, no console errors. Covered:
  • tooltip and panel open and close
  • jump links
  • the player never sees the hidden era or the DM note
  • 400px with no horizontal scroll
  • reduced motion
  • the loop stops at rest
  • Era look Save and Cancel
  • the era editor's hidden flag, note and lore page
• Live captures of the real build were shown to Key Maker (Sign-offs card "Calendar eras: where the info and the look settings ended up"). The era form, the begins label, the tooltip and the tint clipping were tidied after the first captures.
• Adversarial review. Fixed after review:
  • A calendar remounted by the Calendars page opener reused a dead painter, so no colours showed and its loop could not rest.
  • Repeat-rule anchors now pass the secret-era filter.
• Follow-up: Calendar: a Scribe's own events inside a hidden era vanish for them #982 (a Scribe's own events inside a hidden era vanish for them).

Tenet self-check

• T-B1 security: server-side hiding on every era and event read path, listed above
• T-B2 plugin isolation: no cross-plugin imports; the lore link uses the core entities table through the existing viewable-entities gate
• T-B3 production UI: transitions, loading and error states in the panel, reduced motion, ease to still (Every looping animation slows to still when you step away and restarts when you're back #935), keyboard and Escape
• T-B4 dual-audience docs: calendar .ai.md covers the era look, hidden eras and the panel

🤖 Generated with Claude Code

https://claude.ai/code/session_01FWwWUo8dgxEwNJ8SWFdJuj

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Generated by Claude Code

[keyxmakerx]

Build & Test and Fresh-DB Migration Replay will be red here, and the cause isn't this PR. Main currently has two core migrations numbered 000036 (000036_stashes and 000036_campaign_book_edits), so on main itself both checks are red at 6a5bf17.

I first carried #977's renumber into this branch. That tripped check-migration-immutability.sh, because the guard sees renaming 000036_stashes as deleting an existing migration; #977 is red on the same guard. So I dropped that commit, and this PR now fails exactly the way main does.

The fix belongs in #977: either an allowed exception in the guard for a never-deployed renumber, or a different fix. Once #977 lands, I'll merge main into this branch and the checks should go green.

Locally, with the stashes migration renumbered for the run only, go test ./internal/plugins/calendar/... against MariaDB passes (323 tests), and so does everything else listed in the test plan.

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Generated by Claude Code