fix(upgrade): replace Bun.mmap with arrayBuffer on macOS to prevent SIGKILL

[BYK]

Summary

`Bun.mmap()` always requests `PROT_WRITE` in its implementation regardless of the `shared` flag. On macOS, AMFI code signing enforcement sends an uncatchable `SIGKILL` for any writable mapping (`MAP_SHARED` or `MAP_PRIVATE`) on code-signed Mach-O binaries — which all Bun-compiled binaries are.

PR #339's `{ shared: false }` (MAP_PRIVATE) fix was insufficient. Sentry telemetry confirmed: zero successful macOS upgrade traces from delta-enabled versions, while Linux worked fine.

Fix

Platform-conditional old file loading in `src/lib/bspatch.ts`:

• macOS: `new Uint8Array(await Bun.file(oldPath).arrayBuffer())` — reads into memory (~100 MB heap, freed after patching)
• Linux: `Bun.mmap(oldPath)` — keeps zero-heap memory-mapped path

const oldFile =
  process.platform === "darwin"
    ? new Uint8Array(await Bun.file(oldPath).arrayBuffer())
    : Bun.mmap(oldPath);

Evidence

Condition	Upgrade Traces	Outcome
macOS + pre-delta versions	26	✅ All successful
macOS + delta-enabled versions	0	❌ Process killed before telemetry flush
Linux + delta-enabled versions	4	✅ All successful

[github-actions]

Semver Impact of This PR

🟢 Patch (bug fixes)

📋 Changelog Preview

This is how your changes will appear in the changelog.
Entries from this PR are highlighted with a left border (blockquote style).

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New Features ✨

Trace

• Add cursor pagination to trace list by BYK in #324
• Add sentry trace logs subcommand (Add CLI support for fetching logs associated with a trace #247) by BYK in #311

Other

• (api) Add --data/-d flag and auto-detect JSON body in fields by BYK in #320
• (formatters) Render all terminal output as markdown by BYK in #297
• (install) Add Sentry error telemetry to install script by BYK in #334
• (issue-list) Global limit with fair distribution, compound cursor, and richer progress by BYK in #306
• (log-list) Add --trace flag to filter logs by trace ID by BYK in #329
• (logger) Add consola-based structured logging with Sentry integration by BYK in #338
• (project) Add project create command by betegon in #237
• (upgrade) Add binary delta patching via TRDIFF10/bsdiff by BYK in #327

Bug Fixes 🐛

Api

• Use numeric project ID to avoid "not actively selected" error by betegon in #312
• Use limit param for issues endpoint page size by BYK in #309
• Auto-correct ':' to '=' in --field values with a warning by BYK in #302

Formatters

• Expand streaming table to fill terminal width by betegon in #314
• Fix HTML entities and escaped underscores in table output by betegon in #313

Setup

• Suppress agent skills and welcome messages on upgrade by BYK in #328
• Suppress shell completion messages on upgrade by BYK in #326

Upgrade

• Replace Bun.mmap with arrayBuffer on macOS to prevent SIGKILL by BYK in #340

• Use MAP_PRIVATE mmap to prevent macOS SIGKILL during delta upgrade by BYK in #339

Other

• (ci) Generate JUnit XML to silence codecov-action warnings by BYK in #300
• (install) Fix nightly digest extraction on macOS by BYK in #331
• (nightly) Push to GHCR from artifacts dir so layer titles are bare filenames by BYK in #301
• (project create) Auto-correct dot-separated platform to hyphens by BYK in #336
• (region) Resolve DSN org prefix at resolution layer by BYK in #316
• (test) Handle 0/-0 in getComparator anti-symmetry property test by BYK in #308
• (trace-logs) Timestamp_precise is a number, not a string by BYK in #323

Documentation 📚

• Document SENTRY_URL and self-hosted setup by BYK in #337

Internal Changes 🔧

Api

• Upgrade @sentry/api to 0.21.0, remove raw HTTP pagination workarounds by BYK in #321
• Wire listIssuesPaginated through @sentry/api SDK for type safety by BYK in #310

Other

• (craft) Add sentry-release-registry target by BYK in #325

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[github-actions]

Codecov Results 📊

✅ 2681 passed | Total: 2681 | Pass Rate: 100% | Execution Time: 0ms

📊 Comparison with Base Branch

Metric	Change
Total Tests	—
Passed Tests	—
Failed Tests	—
Skipped Tests	—

✨ No test changes detected

All tests are passing successfully.

✅ Patch coverage is 100.00%. Project has 3108 uncovered lines.
✅ Project coverage is 82.62%. Comparing base (base) to head (head).

Coverage diff

@@            Coverage Diff             @@
##          main       #PR       +/-##
==========================================
+ Coverage    82.62%    82.62%        —%
==========================================
  Files          127       127         —
  Lines        17880     17883        +3
  Branches         0         0         —
==========================================
+ Hits         14772     14775        +3
- Misses        3108      3108         —
- Partials         0         0         —

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