⚡ Bolt: Replace O(N^2) array spread with amortized O(1) Map push in useSchedule

[anyulled]

💡 What:
Replaced an array spread operation [...existing, session] inside a loop with an if/else block that pushes session into the existing array or creates a new one inside hooks/useSchedule.ts.

🎯 Why:
Using the array spread operator within a loop structure creates a new array on every iteration. This leads to an $O(N^2)$ time complexity for grouping and incurs a significant Garbage Collection (GC) overhead from constant intermediate array object creations. By mutating the existing array via push(), we achieve an amortized $O(1)$ append operation, speeding up the grouping logic.

📊 Impact:

• Reduces the time complexity of the schedule grouping logic from $O(N^2)$ to $O(N)$.
• Substantially reduces temporary object allocations, which lessens pressure on the garbage collector.

🔬 Measurement:

• Run npm run test (including __tests__/hooks-useSchedule.test.ts) to ensure the grouping output format is unchanged.
• Use a performance profiler on pages displaying the schedule (which relies on useSchedule.ts) over large mock datasets to observe improvements in synchronous Javascript execution time.

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PR created automatically by Jules for task 13518155474737365169 started by @anyulled

Summary by CodeRabbit

• Refactor
  • Optimized internal schedule grouping logic for improved performance.

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Project	Deployment	Actions	Updated (UTC)
devbcn	Ready	Preview, Comment	Apr 3, 2026 8:39am

[qodo-code-review]

Review Summary by Qodo

Optimize schedule grouping with direct array mutation

✨ Enhancement

Walkthroughs

Description

• Replace O(N²) array spread with O(1) Map push operation
• Eliminate unnecessary array allocations in schedule grouping loop
• Reduce garbage collection pressure from intermediate objects
• Improve synchronous JavaScript execution performance

Diagram

flowchart LR
  A["Loop sessions"] --> B["Get existing array"]
  B --> C{"Array exists?"}
  C -->|No| D["Create new array"]
  C -->|Yes| E["Push to existing"]
  D --> F["Set in Map"]
  E --> F
  F --> G["O(1) amortized operation"]

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File Changes

1. hooks/useSchedule.ts Performance optimization +6/-2

Replace array spread with direct mutation in grouping

• Replaced array spread operator [...existing, session] with conditional logic
• Check if array exists in Map before creating or mutating
• Use push() method to append sessions to existing arrays
• Eliminates O(N²) complexity from repeated array allocations

hooks/useSchedule.ts

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[qodo-code-review]

Code Review by Qodo

🐞 Bugs (0) 📘 Rule violations (0) 📎 Requirement gaps (0)

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[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: eb687d3c-f014-4f12-af45-ec4c9baaa8b9

📥 Commits

Reviewing files that changed from the base of the PR and between 81f3c53 and 725d4fd.

📒 Files selected for processing (1)

• hooks/useSchedule.ts

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📝 Walkthrough

Walkthrough

The getSchedule function optimization: instead of creating new arrays via spread operator when grouping sessions by time, the code now retrieves the existing array from the map and mutates it in-place using push(). The functional outcome remains unchanged.

Changes

Cohort / File(s)	Summary
Schedule Grouping Optimization hooks/useSchedule.ts	Refactored session grouping to use in-place array mutation (push()) instead of creating new arrays via spread operator on each insertion into the sessionsByTime map.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related PRs

• ⚡ Bolt: Add React.cache to getSchedule hook #24: Modifies the same getSchedule function, wrapping it with React.cache and adding cache-related tests in parallel with this optimization.
• ⚡ Bolt: Optimize talk grouping performance #105: Applies the identical optimization pattern (spread → in-place push) to groupTalksByTrack in hooks/useTalks.ts.

Suggested labels

size/XXL

Poem

🐰 Arrays grouped with speeds so fleet,
No spreading arrays in the heat,
Just push and mutate, quick and clean,
The fastest grouping you've seen! ⚡

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the main optimization: replacing O(N²) array spread with O(1) Map push in useSchedule, which directly matches the changeset's core improvement.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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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 bolt/optimize-use-schedule-13518155474737365169

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[gemini-code-assist]

Code Review

This pull request refactors the session grouping logic in hooks/useSchedule.ts to improve performance by mutating the existing session array instead of creating a new one with the spread operator. I have no feedback to provide.