Deferred: maplibre-gl 5 → 6 upgrade (breaking: default-import removed + leaflet adapter has no v6 release)

[Yeraze]

Dependabot opened #4646 for maplibre-gl 5.24.0 → 6.2.0. Closed and ignored (see `.github/dependabot.yml` update); tracking here so the eventual upgrade lands deliberately.

Blockers

1. `@maplibre/maplibre-gl-leaflet` has no v6 support

The leaflet adapter we use for `VectorTileLayer` (`src/components/VectorTileLayer.tsx`) is stuck at 0.1.3 — no release for a year — and its peer range explicitly stops at v5:

```
"maplibre-gl": "^2.4.0 || ^3.3.1 || ^4.3.2 || ^5.0.0"
```

We can't move to v6 unless one of:

• Upstream ships an adapter release supporting v6, OR
• We rewrite `VectorTileLayer.tsx` to consume maplibre-gl directly (skip the leaflet adapter) — non-trivial because our whole raster/vector branch in `BaseMap` (from map-consolidation epic refactor(maps): consolidate 10 independent Leaflet maps into a shared BaseMap shell + composable layer library #4047) assumes leaflet is the common shell.

Upstream tracking: watch `@maplibre/maplibre-gl-leaflet` releases for a version bump. If the project stays dormant, plan for the rewrite instead.

2. Default import gone (ESM-only v6)

CI on #4646 failed on this — dependabot's diff, unmodified, hits:

```
error TS1192: Module '.../maplibre-gl/dist/maplibre-gl' has no default export.
src/components/map/Base3DMap.tsx
src/components/MapAnalysis/Follow3DController.tsx
src/components/MapAnalysis/MapAnalysisCanvas.tsx
```

Codemod is small — swap `import maplibregl from 'maplibre-gl'` for `import * as maplibregl from 'maplibre-gl'` (or named imports) — but has to happen in the same PR as the version bump, or CI stays red.

3. Other breaking changes to walk through

From the v5→v6 migration guide:

• `Map` composes `Camera` instead of extending it — `map.transform` is gone, use the public API.
• All events are real classes now; `MapDataEvent` split into `MapSourceDataEvent | MapStyleDataEvent`.
• `styleimagemissing` is notify-only — supply images via `Map.setMissingStyleImageResolver`.
• `GeoJSONSource.setData` no longer takes `waitForCompletion` and doesn't return `this`.
• Style spec v25 throws warnings on legacy expressions.
• `zoomLevelsToOverscale` default changed to 4 (affects `queryRenderedFeatures` and some label placement).

Each needs verification against our actual usage in 3D map / analysis canvas / follow controller.

Suggested unblock plan

1. Open an issue on `@maplibre/maplibre-gl-leaflet` requesting v6 support (or check if one exists).
2. If dormant, scope the `VectorTileLayer` rewrite as a prerequisite.
3. Only then land maplibre-gl 6, in the same PR as the import codemod + Map/event/style-spec fixes, verified against the 3D map surface.

[Yeraze]

Upstream re-check (2026-08-11)

Verified the state of blocker #1 (@maplibre/maplibre-gl-leaflet v6 support). Still fully blocked — waiting is not realistic on any near-term horizon.

Versions today

Package	Then	Now
maplibre-gl (latest)	6.2.0	6.3.0 (we're on 5.24.0)
@maplibre/maplibre-gl-leaflet	0.1.3, peer ^5.0.0	unchanged — 0.1.3, peer still caps at ^5.0.0

Upstream activity

• A v6 tracking issue exists: maplibre-gl-leaflet#93 "Upgrade peer dependencies to allow Maplibre GL 6.0.0" (opened 2026-07-28 by a third party). Zero comments, no maintainer reply, no assignee.
• No PR addresses v6. The only open PRs are two Dependabot bumps and an unrelated attribution fix ([BUG] v1.11.0 can't connect tcp node #86).
• Repo cadence is slow/single-track: last commit on main was 2026-03-16 (githack examples fix); the actual v5-compat work landed July 2025, then 0.1.3 was tagged and it's been quiet since. Not archived, but v6 is not in flight.
• No fork has done the work — of 49 forks, the only two pushed after upstream's last commit just mirror upstream (no v6 branch to pin to).

Recommendation

The v5 support that unblocks us today took ~a year and one contributor's PR. Betting the v6 upgrade on the same project delivering again — with no maintainer having even acknowledged #93 — is an indefinite timeline.

If maplibre-gl 6 becomes a priority, the VectorTileLayer.tsx rewrite (blocker #2) is the realistic unblock path, not waiting on upstream. Otherwise keep this deferred and subscribe to upstream #93 as the trigger.