docs(engine-plan): full v0.5.1299 baseline table and re-ordered backlog

[proggeramlug]

The plan's performance backlog topped out at 6.27x and omitted two kernels entirely — because until today they crashed rather than ran (#7495, #7516/#7529 fixed them).

Replaces it with all twelve app-pattern kernels plus the JSON polyglot legs, measured on the pinned quiet mini at v0.5.1299 (AC power, CPU-quiet gate passed, node 22.23.1 / bun 1.3.14, 11 runs/cell).

Two findings drive the re-ordering:

• object_deep_clone is 37.5x bun (657 ms vs 17.5 ms) — worst cell by 3x over the next, newly measurable. Now perf: object_deep_clone is 37.5x bun (657ms vs 17.5ms) — the worst row in the public artifact, newly visible now that it runs #7533, first in the queue, profile-first with an explicit A/B against f06270d06 to settle whether today's rooting re-reads are material on a spread-heavy workload.
• The lazy tape is a net negative on scans: optimized is 2.2x slower than unoptimized on field_access (2984 vs 1350 ms) at 3.6x the RSS — while being a 6.8x win on roundtrip, where Perry beats bun and node and lands within ~8% of Rust serde_json. json tape: full-array scans pay 2.3× the direct parser (field_access 2981ms vs bun 223) — decomposition + roadmap #7478.

Also adds #7502 to the ordering: nine mechanics of the shipped root lowering have no assertion anywhere, and today's ~20 rooting bugs were all found by hand because nothing else can find them.

Docs only.

Summary by CodeRabbit

• Documentation

  • Updated engine planning documentation with the latest benchmark results, performance priorities, and tracked issues.
  • Added a changelog entry covering the v0.5.1299 engine baseline and performance backlog.

• Chores

  • Incremented the application version to 0.5.1301.

[coderabbitai]

Caution

Review failed

The pull request is closed.

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: e6c5d915-5f93-4c70-ab66-df91525521fb

📥 Commits

Reviewing files that changed from the base of the PR and between fc5e56e and 668f26f.

⛔ Files ignored due to path filters (1)

• Cargo.lock is excluded by !**/*.lock

📒 Files selected for processing (4)

• CLAUDE.md
• Cargo.toml
• changelog.d/7534-plan-baseline-1299.md
• docs/engine-plan.md

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📝 Walkthrough

Walkthrough

The project version is updated to 0.5.1301. The changelog and engine plan document the v0.5.1299 benchmark baseline, JSON measurements, and reordered performance backlog.

Changes

Release and engine plan updates

Layer / File(s)	Summary
Release metadata and changelog CLAUDE.md, Cargo.toml, changelog.d/...	Updates the documented and workspace versions to 0.5.1301 and adds the v0.5.1299 baseline changelog.
Benchmark baseline measurements docs/engine-plan.md	Records twelve-kernel timings and JSON polyglot benchmark results for the v0.5.1299 public baseline.
Performance backlog priorities docs/engine-plan.md	Reorders work for deep cloning, JSON scans, GC layout, write barriers, rooting coverage, and later ratchet tasks.

Estimated code review effort: 2 (Simple) | ~10 minutes

Possibly related PRs

• PerryTS/perry#6751: Introduces the changelog fragment and version documentation workflow used here.
• PerryTS/perry#7222: Also updates versions in CLAUDE.md and Cargo.toml.
• PerryTS/perry#7405: Also updates engine performance benchmarks and backlog priorities.

Suggested reviewers: thehypnoo

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch docs/engine-plan-baseline-1299

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