fix(server): troop duplication by cosyntxd · Pull Request #6089 · openfrontio/OpenFrontIO

cosyntxd · 2026-10-23T04:15:22Z

When a cancelled attack finishes at the same tick as a new attack starts, the game would add troops to the new front without resetting troops of original attack, duplicating troops. Tests pass and verified the fix stops the dupe on localhost.

Bug was discussed in the Discord server and could easily be reproduced. This is a hotfix and stops exploit.

No UI or text changes.

syntxd

When a cancelled attack finishes at the same tick as a new attack starts, the game would add troops to the new front without resetting troops of original attack, duplicating troops. Tests pass and verified fix stops the dupe on localhost

CLAassistant · 2026-10-23T04:15:31Z

All committers have signed the CLA.

coderabbitai · 2026-10-23T04:15:57Z

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packages/engine/src/execution/AttackExecution.ts
tests/Attack.test.ts

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Walkthrough

AttackExecution.tick now checks for an inactive attack before processing a completed retreat. Tests cover troop totals when a retreating attack is absorbed as its retreat completes.

Changes

Retreat refund handling

Layer / File(s)	Summary
Check inactive attacks before retreat processing `packages/engine/src/execution/AttackExecution.ts`, `tests/Attack.test.ts`	The tick method returns for inactive attacks before processing completed retreats. Tests check troop totals when an attack is absorbed as its retreat completes and a follow-up attack merges or the defender attacks back.

Priority: ➖ Normal

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

Change: Bug fix

Suggested reviewers: evanpelle, flopinguin

Merge Risk: ⚪ Minimal · up to 49ed9

The change targets duplicate troop refunds when attacks coincide with a completed retreat. No actionable merge-blocking issue is established by the supplied evidence; normal checks remain appropriate.

Pre-merge checks: 4 · 1

Failed checks: 1 warning

Check name	Status	Explanation	Resolution
Docstring Coverage		Docstring coverage is 33.33% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 3 functions across 2 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

Passed checks: 4 passed

Check name	Status	Explanation
Title check		The title names the main change: a fix for troop duplication on the server. It matches the objective of stopping a cancelled attack from duplicating troops when a new attack starts on the same tick. I…
Description check		The description states the bug: a cancelled attack that finishes on the same tick as a new attack adds troops to the new front without resetting the original attack's troops. It also says tests pass a…
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.

Full details: Title check

Explanation

The title names the main change: a fix for troop duplication on the server. It matches the objective of stopping a cancelled attack from duplicating troops when a new attack starts on the same tick. It is short and specific.

Full details: Description check

Explanation

The description states the bug: a cancelled attack that finishes on the same tick as a new attack adds troops to the new front without resetting the original attack's troops. It also says tests pass and the fix was checked on localhost. This relates directly to the changeset in AttackExecution.ts and the new tests in Attack.test.ts.

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_{Retreat completes; the tick checks first
Inactive attacks return without a refund
New attacks merge, troop totals stay checked
Defenders answer; tests follow the flow
Duplicate refunds find no way through}

_{Comment @coderabbitai help to get the list of available commands.}

coderabbitai

Actionable comments posted: 1

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Inline comments:
Review comments at @packages/engine/src/execution/AttackExecution.ts:
- Around line 177-178: Add a regression test for same-tick merging of a
cancelled outgoing attack into a new attack targeting the same destination.
Verify the new attack receives the troops exactly once and the old
AttackExecution does not refund troops after outgoing.setTroops(0) clears them.

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packages/engine/src/execution/AttackExecution.ts

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VariableVince · 2026-10-23T11:12:27Z

(Merged main to get CI green [apart from Milestone which a reviewer will assign]. After the stack of #6074 landed.)

Celant

Nice catch, and thanks for turning this around quickly. I reproduced it locally: the retreating attack's execution still hits the retreated() branch on the next tick even after it's been merged and deleted, so it refunds whatever troops() still holds. Zeroing it closes the merge case. The opposing-attack cancel loop just above has the same hole though, see inline.

…sorbed The same-tick dupe also hit the opposing-attack cancel-out path, which deleted the incoming attack without zeroing it. Check isActive() before retreated() in tick() so a deleted attack can never refund, covering both the merge and cancel-out paths, and add regression tests for each. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Celant · 2026-10-23T15:41:04Z

Since this is live I've pushed the rest of the fix to your branch so we can get it out. Instead of zeroing troops at each delete site, tick() now checks isActive() before retreated(), so an attack that another attack's init already absorbed or cancelled can never refund. That covers your merge case and the opposing-attack case. I dropped the setTroops(0) line since it's redundant now. I also added two tests in tests/Attack.test.ts that land the new attack on the exact tick the retreat completes: on main both refund about 75% of the absorbed troops, and with only the merge fix the cancel-out one still does. Thanks again for tracking this down.

github-actions · 2026-10-23T15:43:10Z

🤖 Claude Code Review

Verdict: looks good — no issues found (0 critical, 0 major, 0 minor).

Checked for bugs and CLAUDE.md compliance. Moving the isActive() check ahead of the retreated() refund in AttackExecution.tick is correct: attack.delete() is only called when the troops have already been moved elsewhere (merged into a new attack, cancelled out by an opposing attack, troops < 1, or a prior retreat). So an inactive attack should never be refunded. The engine change comes with tests that cover both the merge path and the opposing-attack cancel path, as CLAUDE.md requires.

github-actions · 2026-10-23T15:52:49Z

🤖 Claude Code Review

Reviewed range: 49ed992..dd3b8f2

Verdict: No issues found. 0 findings (0 high, 0 medium, 0 low).

The only change in this range is a merge of main (dd3b8f2 Merge branch main into duper-trooper). It brings in the AZERTY/keybind display changes from #5568 (KeyboardLayout.ts, Utils.ts, UnitDisplay.ts, HelpModal.ts, Platform.ts and others). None of it touches this PR's own files (packages/engine/src/execution/AttackExecution.ts, tests/Attack.test.ts), and it doesn't conflict with the troop-duplication fix. So there was nothing new in this PR to review, and the earlier review of 49ed992 still stands.

Checked for bugs and CLAUDE.md compliance.

github-actions · 2026-10-23T15:56:26Z

🍒 Cherry-picked onto v35 as a2d20f8.

When a cancelled attack finishes at the same tick as a new attack starts, the game would add troops to the new front without resetting troops of original attack, duplicating troops. Tests pass and verified the fix stops the dupe on localhost. Bug was discussed in the Discord server and could easily be reproduced. This is a hotfix and stops exploit. No UI or text changes. syntxd --------- Co-authored-by: VariableVince <24507472+VariableVince@users.noreply.github.com> Co-authored-by: Josh <josh@openfront.io> Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com> (cherry picked from commit 8944c50)

fix(server): troop duplication

c442426

When a cancelled attack finishes at the same tick as a new attack starts, the game would add troops to the new front without resetting troops of original attack, duplicating troops. Tests pass and verified fix stops the dupe on localhost

github-project-automation Bot added this to OpenFront Release Management Oct 23, 2026

github-project-automation Bot moved this to Triage in OpenFront Release Management Oct 23, 2026

cosyntxd requested a review from a team as a code owner October 23, 2026 04:15

github-actions Bot assigned cosyntxd Oct 23, 2026

github-actions Bot added the small-fix Small fix (≤ 50 lines) — auto-applied by PR gate label Oct 23, 2026

coderabbitai Bot requested changes Oct 23, 2026

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Comment thread packages/engine/src/execution/AttackExecution.ts Outdated

github-project-automation Bot moved this from Triage to Development in OpenFront Release Management Oct 23, 2026

Merge branch 'main' into duper-trooper

e9efc7e

Celant added this to the v35 milestone Oct 23, 2026

Celant reviewed Oct 23, 2026

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Comment thread packages/engine/src/execution/AttackExecution.ts Outdated

openfrontio deleted a comment from github-actions Bot Oct 23, 2026

Celant added the ready-for-review label Oct 23, 2026

coderabbitai Bot approved these changes Oct 23, 2026

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Celant approved these changes Oct 23, 2026

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Merge branch 'main' into duper-trooper

dd3b8f2

Celant enabled auto-merge (squash) October 23, 2026 15:51

Celant merged commit 8944c50 into openfrontio:main Oct 23, 2026
14 checks passed

github-project-automation Bot moved this from Development to Complete in OpenFront Release Management Oct 23, 2026

Celant deployed to backport October 23, 2026 15:55 — with GitHub Actions Active

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fix(server): troop duplication - #6089

fix(server): troop duplication#6089
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