fix: guard weighted-average merge against zero outputAmountSum in historicalOrderCharts

[thedavidmeister]

Summary

• Fixes a divide-by-zero in prepareHistoricalOrderChartData when two or more trades share a timestamp and their outputVaultBalanceChange.amount values sum to zero
• When outputAmountSum === 0, falls back to unweighted mean of ioratio values instead of dividing by zero (which would produce NaN or ±Infinity)
• Adds an inline vitest case covering the fallback path: two zero-amount trades at the same timestamp → verifies the result is finite and equals the unweighted mean

Note: this is a pure data computation function with no rendering, so a UI screenshot is not applicable.

Closes #2766

Co-Authored-By: Claude noreply@anthropic.com

Summary by CodeRabbit

• Bug Fixes

  • Fixed historical order chart merging for same-timestamp trades by safely handling cases where total output is zero, preventing invalid derived ratios and ensuring the merged chart value resolves to 0 instead of error-prone results.

• Tests

  • Added Vitest coverage for same-timestamp edge cases where output sums to zero and per-trade ratio inputs are non-finite, asserting the merged chart output is 0.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

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Reviewing files that changed from the base of the PR and between 671e15f and b3b5538.

📒 Files selected for processing (1)

• packages/ui-components/src/lib/services/historicalOrderCharts.ts

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📝 Walkthrough

Walkthrough

prepareHistoricalOrderChartData now guards the same-timestamp merge when total output amount is zero, using a fallback mean instead of producing non-finite values. A new Vitest case covers zero-summing output amounts.

Divide-by-zero fix and test

Layer / File(s)	Summary
Zero-output-sum guard and coverage packages/ui-components/src/lib/services/historicalOrderCharts.ts	The same-timestamp merge branch now uses an unweighted mean of finite per-trade ratios when outputAmountSum === 0, and a new Vitest case asserts the merged chart value is 0 for zero-summing trades.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

Possibly related PRs

• rainlanguage/raindex#2763: Related changes in historicalOrderCharts.ts also adjust zero-output handling for chart data and add coverage around non-finite values.

Poem

🐇 I hopped to the chart with a tiny fix in sight,
Zero sums no longer derail the graph tonight.
Finite hops together, neat and clear,
The merge stays steady when zeros appear.
No NaN shadows, no Infinity tide—
Just a bunny-approved mean rolling on with pride.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the divide-by-zero fix in historicalOrderCharts.
Linked Issues check	✅ Passed	The changes address #2766 by guarding zero output sums and adding a test for the same-timestamp merge case.
Out of Scope Changes check	✅ Passed	The patch stays within the requested data-computation fix and associated test coverage, with no unrelated changes.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch 2026-06-17-issue-2766-historical-chart-divide-zero

Warning

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🔧 ESLint

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packages/ui-components/src/lib/services/historicalOrderCharts.ts

Oops! Something went wrong! :(

ESLint: 8.57.1

Error: ESLint configuration in --config is invalid:

• Unexpected top-level property "__esModule".

  at ConfigValidator.validateConfigSchema (/node_modules/@eslint/eslintrc/dist/eslintrc.cjs:2177:19)
  at ConfigArrayFactory._normalizeConfigData (/node_modules/@eslint/eslintrc/dist/eslintrc.cjs:3019:19)
  at ConfigArrayFactory._loadConfigData (/node_modules/@eslint/eslintrc/dist/eslintrc.cjs:2984:21)
  at ConfigArrayFactory.loadFile (/node_modules/@eslint/eslintrc/dist/eslintrc.cjs:2850:40)
  at createCLIConfigArray (/node_modules/@eslint/eslintrc/dist/eslintrc.cjs:3660:35)
  at new CascadingConfigArrayFactory (/node_modules/@eslint/eslintrc/dist/eslintrc.cjs:3735:29)
  at new CLIEngine (/node_modules/eslint/lib/cli-engine/cli-engine.js:617:36)
  at new ESLint (/node_modules/eslint/lib/eslint/eslint.js:430:27)
  at Object.execute (/node_modules/eslint/lib/cli.js:410:24)
  at async main (/node_modules/eslint/bin/eslint.js:152:22)

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@packages/ui-components/src/lib/services/historicalOrderCharts.ts`:
- Around line 51-55: The fallback calculation for ioratioAverage when
outputAmountSum === 0 does not guard against d.value being non-finite (Infinity
or NaN), which can occur when outputVaultBalanceChange.formattedAmount is "0"
from the initialization at lines 22-25. Filter out non-finite values from the
fallback average calculation by adding a check to ensure each d.value is finite
before including it in the reduce operation. Additionally, update the test
fixture that currently hardcodes "100" to test with "0" values that would expose
this non-finite path and verify the fix handles it correctly.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

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Run ID: 68d77525-228b-4304-b28e-e4ae2687eef8

📥 Commits

Reviewing files that changed from the base of the PR and between 175e84a and 671e15f.

📒 Files selected for processing (1)

• packages/ui-components/src/lib/services/historicalOrderCharts.ts

[thedavidmeister]

screenshot pending (manual): historicalOrderCharts.ts produces data for lightweight-charts canvas rendering — canvas output requires a headless Chromium harness to screenshot; the change itself is a computation fix (unweighted-mean fallback when outputAmountSum is 0) with no layout change