bugfix

# Bugfix Fix bugs listed in `BUGS.md`. If `$ARGUMENTS` is provided, only fix bugs matching the given package or file names. Otherwise, fix all bugs. ## Step 0: Read BUGS.md 1. Read `BUGS.md` at the repo root. 2. Parse each bug entry: file path, line range, description. 3. If `$ARGUMENTS` filters to specific packages/files, select only matching bugs. 4. Skip any bugs already marked as fixed (checkbox `[x]`). ## Step 1: For each bug ### 1a. Understand the bug - Read the affected file(s) and surrounding context. - Read existing tests for the affected package. - Confirm the bug is real by analyzing the code path described. ### 1b. Write a regression test - Add a test that **reproduces the bug** — it must exercise the exact code path described in the bug entry. - The test should **fail** (panic, wrong result, etc.) without the fix and **pass** after the fix. - Follow existing test patterns in the package. - Name the test descriptively: `TestFoo_BugDescription`. ### 1c. Verify the test fails - Run the test to confirm it fails or panics without the fix. - If the test passes without the fix, the bug may already be fixed or the test doesn't cover the right path — investigate and adjust. ### 1d. Apply the minimal fix - Make the smallest change that fixes the bug. - Do not refactor surrounding code. - Do not change behavior for non-buggy code paths. ### 1e. Verify the fix 1. Run the specific test to confirm it passes. 2. Run `go test ./...` for the affected package t...