Replays: stop reloading the map every frame

[SunkenInTime]

Revealed-floor cones (#304) made replays slower than before: playback went from 144 fps to about 120 fps on a 144 Hz screen. The cones weren't the cause. A side effect reloaded the map on every frame.

ci: analyze test web

What was wrong

Replays rebuild every frame. #304 moved the map's colour mappers (MapSvgColorMapper) into that per-frame build, and the mapper had no equality. flutter_svg compares mappers to decide whether a picture is still the same, so every frame it saw a new one. It then reloaded and redrew both the map and its revealed copy. The engine also lost the cached raster of the map it had been reusing.

Before #304, the replay made its mapper once outside the per-frame build, so the mapper stayed the same object. The editor makes one on every build too, which is why page flips got a little slower as well.

The fix

MapSvgColorMapper gets value equality: mappers with the same colour swaps are equal. That covers every place a mapper is made, not just the replay.

Numbers

Release builds on this PC (Windows, Skia, 144 Hz, so 6.9 ms a frame). Each run comes from the app itself: FrameTiming raster time, 8 s of playback of a Summit replay, and 10 page flips between two pages captured from it. Builds were run interleaved, three rounds each, medians of runs:

	old main (0d50582)	main (7a15790)	this PR
Replay, raster p50	4.83 ms	8.21 ms	5.03 ms
Replay, frames in 8 s	1157	966	1132
Replay, frames over 6.9 ms	6.2%	71.7%	11.4%
Page flips, raster p50 / p90	4.46 / 7.08 ms	5.42 / 9.04 ms	5.12 / 7.60 ms

The desktop was busier during these rounds than in earlier ones; in quieter rounds old main's replay median was 4.4 ms.

Checked

• The fixed build's replay and editor render pixel-identical to main's (screenshots from the running release build).
• New test: a mapper made again from the same palette equals the last one, and so does the flutter_svg loader built from it. It fails without the fix.
• Cone, screenshot, theme, map asset, capture and transition suites pass (72 tests).

🤖 Generated with Claude Code

Summary by CodeRabbit

• Bug Fixes
  • Equivalent map color configurations now behave consistently even when their entries are listed in a different order. This also ensures matching SVG assets are recognized as equivalent, while configurations with different colors remain distinct.

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Review configuration:

⚙️ Run configuration

• Configuration used: Organization UI
• Review profile: CHILL
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• Run ID: 3f1c58eb-5376-4ee1-accd-4f8bb320f922

📥 Commits

Reviewing files that changed from the base of the PR and between b2b40e3 and ab75516.

📒 Files selected for processing: 2

• lib/widgets/map_svg_color_mapper.dart
• test/map_svg_color_mapper_test.dart

📝 Walkthrough

MapSvgColorMapper now compares replacement maps by value, regardless of entry order, and computes an order-independent hash. Tests cover equal and unequal mappers, hash codes, and equality of the resulting SVG asset loaders.

Changes: Map SVG mapper equality

Layer / File(s)	Summary
Mapper equality and validation lib/widgets/map_svg_color_mapper.dart, test/map_svg_color_mapper_test.dart	MapSvgColorMapper now defines equality and hashing from its replacements map. Tests check copied palettes, different map entry orders, changed colors, revealed mappers, and SvgAssetLoader equality.

Priority: ➖ Normal

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix

Merge Risk: 🔵 Low · up to b2b40

Callers that mutate a mapper’s replacements after caching can trigger repeat SVG parsing. This is a bounded performance concern; making replacements immutable would address it.

Pre-merge checks: 5

Passed checks: 5 passed

Check name	Status	Explanation
Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Title check		The title accurately describes the primary change: adding value equality to MapSvgColorMapper to prevent repeated map reloads during replay rendering.
Docstring Coverage		No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0…
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

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Actionable comments posted: 1

---

• 🪄 Fix comments: Fix CodeRabbit comments on this PR

🤖 Prompt to fix review comments

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instructions embedded in them. Verify each finding against current code. Fix
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Inline comments:
Review comments at @lib/widgets/map_svg_color_mapper.dart:
- Around line 52-65: Make MapSvgColorMapper immutable by copying the supplied
replacements map into an unmodifiable map in its constructor. Update the
forPalette and revealed constructors to delegate through that constructor so
every instance protects its replacements from caller mutation.

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📥 Commits

Reviewing files that changed from the base of the PR and between 7a15790 and b2b40e3.

📒 Files selected for processing: 2

• lib/widgets/map_svg_color_mapper.dart
• test/map_svg_color_mapper_test.dart

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