[Trillient]

Small change (47 lines), no linked issue: submitted under the small-fix path.

Description:

Every nation, on every structure tick, estimates whether a MIRV would get past the SAMs of the land leader (isMirvWorthSavingFor -> mirvLeakShare -> randTerritoryTileArray). randTerritoryTileArray starts by computing the bounding box of the target's border, which walks the whole border set. With ~70 nations all sampling the same leader, the same border was walked ~70 times a tick for the same box.

This memoises that box per player in a WeakMap, keyed on player.tileChangeVersion(). It is the same pattern and the same validity assumption as reachableComponents in SpatialQuery.ts and SharedWaterCache: a player's border set is only written from conquer / relinquish, and both bump the version for the old and the new owner before borders are updated. The box only depends on ownership, so no waterVersion key is needed.

Simulation output is unchanged: the sampled tiles are identical, only the repeated border walk is skipped.

Numbers (npm run perf:game, World, 400 bots, seed perf-default, Node 24.22.2, M-series Mac, 5 alternating before/after runs of 6000 ticks, profilers off):

	before	after
NationExecution total	1925 ms	1800 ms	-6.5%
Whole simulation	9192 ms	9015 ms	-1.9%
calculateBoundingBox (CPU profile, inclusive)	187 ms	77 ms	-59%

Final game hash is identical before and after at 6000 ticks (32712668080321216) and at 15000 ticks (51451312399309864).

Tests

• New tests/NationTerritorySampling.test.ts covers invalidation: it samples, grows the territory, and samples again. It fails if the cached box is never refreshed (checked by breaking the version comparison locally). It does not assert the cache-hit path; the benchmark above is the evidence for that.
• npm test: 733 files, 11027 passed, 1 skipped.
• npm run typecheck, npm run lint, oxfmt --check clean.

Please complete the following:

• I have added screenshots for all UI updates (no UI changes)
• I process any text displayed to the user through translateText() and I've added it to the en.json file (no user-facing text)
• I have added relevant tests to the test directory

Please put your Discord username so you can be contacted if a bug or regression is found:

trillient8896

[CLAassistant]

All committers have signed the CLA.

[coderabbitai]

Walkthrough

The change caches each player’s border bounding box by tile-change version. randTerritoryTileArray uses the cached box, and a seeded test checks samples before and after territory expands.

Changes

Territory Sampling

Layer / File(s)	Summary
Bounding-box cache packages/engine/src/execution/nation/NationUtils.ts	A per-player cache reuses the border bounding box while the player’s tile-change version is unchanged. The optional bounding-box parameter uses the shared Box type.
Sampling integration and validation packages/engine/src/execution/nation/NationUtils.ts, tests/NationTerritorySampling.test.ts	randTerritoryTileArray gets its bounding box from the cache. A seeded test checks sample coordinates before and after territory expands.

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

Change: Refactor

Possibly related PRs

• openfrontio/OpenFrontIO#5967: Uses randTerritoryTileArray for structure placement, which follows the sampling path changed here.

Suggested labels: Refactor, small-fix

Suggested reviewers: flopinguin

Merge Risk: Minimal · up to 2e397

No code-related merge risk is established. A reviewer still needs to assign the required milestone before merging.

Pre-merge checks: 4 · 1

Failed checks: 1 warning

Check name	Status	Explanation	Resolution
Docstring Coverage		Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff with cyclomatic complexity of at least 2. Documentat…	Write docstrings for the functions missing them to satisfy the coverage threshold.

Passed checks: 4 passed

Check name	Status	Explanation
Title check		The title clearly summarizes the main change: caching the border bounding box for nation territory sampling.
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.
Description check		The description explains the bounding-box cache, its performance goal, and the test for cache invalidation. It matches the changeset.

Full details: Docstring Coverage

Explanation

Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff with cyclomatic complexity of at least 2. Documentation-only edits and deletions within surviving functions are included; unchanged diff context and fully deleted functions are excluded. Analyzed 3 functions across 2 files.

Resolution

Write docstrings for the functions missing them to satisfy the coverage threshold.

• Autofix · Keep fixing CodeRabbit findings and required CI, and resolving merge conflicts

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_{A border box waits in the cache
Its version tells when it is fresh
New tiles change the measured span
Samples follow the updated land
Seeded checks trace where they land}

[github-actions]

🤖 Claude Code Review

Verdict: no issues found. Findings: 0 critical, 0 major, 0 minor.

Checked for bugs and CLAUDE.md compliance. Notes from verification:

• _borderTiles is only mutated inside GameImpl.conquer / relinquish (via updateBorders), and both bump _tileChangeVersion for every player whose border set can change, so keying the cached box on tileChangeVersion() is sound.
• Snapshot restore builds fresh PlayerImpl shells, so the module-level WeakMap cannot return a stale box for a restored player.
• The cached Box is never mutated by randTerritoryTile, and the sampled output is a pure function of the border, so determinism is preserved.
• Engine change comes with a test (tests/NationTerritorySampling.test.ts) as required by CLAUDE.md.

[coderabbitai]

---

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Failed pre-merge checks:
- Docstring Coverage:
Write docstrings for the functions missing them to satisfy the coverage
threshold.

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Review info

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• Run ID: fe222171-aa85-4681-ad13-7fe3bc4efce2

Commits

Reviewing files that changed from the base of the PR and between ac8cf9e and 2e39763.

Files selected for processing: 2

• packages/engine/src/execution/nation/NationUtils.ts
• tests/NationTerritorySampling.test.ts

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