"/home/yossef/notes/git/projects/maplibra/risks/Broad Map Layer ID Matching.md"

path: maplibra/risks/Broad Map Layer ID Matching.md

- **fileName**: Broad Map Layer ID Matching
- **Created on**: 2026-06-16 00:48:42

Broad Map Layer ID Matching

Migrated from: obs_vault

Parent: ./Theme Risk Index.md

Severity: high.

Summary

applyThemeToMap() themes and hides layers by checking whether layer IDs contain substrings like water, road, transportation, or building. This can affect app-owned or future custom layers that were not meant to be treated as basemap layers.

Code Evidence

• theme.js: lines 200-226 iterate every style layer and use includes() checks.
• theme.js: lines 223-225 hide every layer whose ID contains building.
• src/app/map-setup.js: lines 78-81 call applyThemeToMap() on every style.load.
• src/ui/ThemeController.js: lines 97-111 can call applyThemeToMap() on theme update.
• src/layers/base/core.js: app-owned building-shell is a layer ID containing building.

Trigger Conditions

• A theme change after app-owned layers are present.
• A style reload after building-shell or other app layers were added.
• A custom basemap or MVF layer with ID containing building, road, water, or transportation.

Likely Symptoms

• building-shell disappears because it gets layout visibility none.
• App-owned layers are recolored as if they were basemap layers.
• Future custom layers behave differently only because their IDs happen to include a substring.
• Theme bugs appear only with certain basemap/style layer names.

Why It Matters

Layer ownership is not encoded in the check. A theme function should not mutate every layer whose ID happens to match a word. This is especially risky because the building shell is a core indoor affordance and visibility managers intentionally treat it as a special layer.

Current Tests

• No direct tests for applyThemeToMap() were found.
• tests/theme-host-mode.test.js covers host style resolution only.
• tests/visibility-manager.test.js covers annotation marker visibility, not shell visibility after theming.

Missing Tests

• applyThemeToMap does not hide app building-shell layer.
• applyThemeToMap only touches known basemap layers.
• theme toggle after addBuildingShell preserves shell visibility.
• custom non-basemap building-like layer is not hidden unless allowlisted.

How To Make Better

• Replace substring matching with an explicit allowlist for known basemap layer IDs.
• Exclude app-owned layer IDs such as building-shell, doors, labels, route layers, and MVF style layers.
• Prefer source-based checks, e.g. only mutate layers from known basemap sources.
• Keep basemap theming separate from indoor-layer theming; indoor layers should be owned by LayerManager.reapplyThemeColors().
• Add regression tests using a mock style with building-shell, building-3d, road-minor, and a custom indoor-road-label.

Debug Steps

1. Inspect map.getStyle().layers before and after a theme change.
2. Check whether building-shell layout visibility changes to none.
3. Confirm whether the affected layer source is a basemap source or an app source.
4. Compare the result with LayerManager visibility state.

See Also

• ../flows/Theme Change.md

• ../modules/Layer Management.md

• ./Layer Visibility Risks.md

• ./Theme Tests and Fix Plan.md

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