fix: preserve Win32 allocator alignment across free and resize

[dogukani]

Problem

image-demo crashes on its first animation frame with Windows exit code 0xC0000374. The canvas store requests a 128-byte-aligned pixel buffer. Win32 Allocator::allocatePreferSpiram returned _aligned_malloc memory for that request, while Allocator::free passed the pointer to std::free. AddressSanitizer identifies this mismatched free in CanvasStore::bindDisplayFramebuffer.

Change

Store the underlying malloc block and requested alignment with each allocation. Return an aligned view, preserve that alignment and existing bytes when resizing, and free the underlying block through the matching allocator.

Verification

• Before the patch, a fresh image-demo build exited on tick 1 with 0xC0000374; AddressSanitizer reported an invalid free at win32_memory.cpp:31.
• With the patch, AddressSanitizer and release builds completed 100 frames and exited 0. The release capture shows the decoded animated Earth.
• A native AddressSanitizer probe passed aligned allocate, resize, and free checks at 1, 8, 16, 128, and 4096 bytes, including data preservation, zero-size behavior, and allocation overflow.
• notes-jsx built, exited 0 through GEA_WINDOWS_VERIFY_ONCE, and rendered its initial notes view.

Summary by CodeRabbit

• Bug Fixes
  • Improved memory allocation and resizing reliability on Windows. Requests with invalid sizes or alignments are handled safely, and allocations respect the required alignment.
  • Resizing now preserves the existing allocation if a replacement cannot be created, and zero-size requests release the allocation and return no memory.

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ℹ️ Recent review info

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📥 Commits

Reviewing files that changed from the base of the PR and between 397cd73 and 2a8157f.

📒 Files selected for processing (1)

• packages/geastack-windows/targets/win32/main/win32_memory.cpp

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📝 Walkthrough

Walkthrough

The Windows allocator now validates allocation sizes and alignments, stores metadata for aligned blocks, and uses that metadata to reallocate and free memory.

Changes

Windows allocator

Layer / File(s)	Summary
Allocation and reallocation packages/geastack-windows/targets/win32/main/win32_memory.cpp	Allocation validates size and alignment, checks for padding overflow, aligns the returned pointer, and records the allocation base, size, and effective alignment. Reallocation preserves alignment, copies the smaller block size, and frees the old block only after a successful allocation. free releases the recorded base pointer.

Priority: ➖ Normal

Estimated code review effort: 3 (Moderate) | ~20 minutes

Change: Bug fix

Suggested reviewers: dashersw

Merge Risk: ⚪ Minimal · up to 2a815

The Windows allocator now records each block's original address and alignment. Aligned allocations are freed and resized correctly, which fixes the reported heap-corruption crash in image-demo. No remaining defect was found in the Windows target code. Shared framework code built from external packages could not be inspected, so owners should confirm it never frees allocator memory with the C runtime directly.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 25.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 4 functions across 1 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: preserving Win32 allocator alignment during deallocation and resizing.

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