---

name: lading-optimize-rescue description: Salvages optimization work lacking benchmarks. Generates missing evidence, validates claims. Bugs discovered during rescue are valuable - invoke /lading-optimize-validate.

Optimization Rescue

Salvage optimization work done without proper benchmarks. Generate evidence, validate claims, and discover bugs hiding in "optimizations."

Valuable Outcomes

Bugs found during rescue are SUCCESS, not failure.

---

Phase 0: Pre-flight

Run /lading-preflight first.

---

Phase 1: Audit

Copygit diff --name-only origin/main...HEAD | grep '\.rs$'

For each change, categorize:

• Preallocation (Vec::with_capacity, String::with_capacity)
• Avoiding clones (borrowing instead of owned)
• Moving allocations out of loops
• Data structure changes
• Potential bug (suspicious patterns)

---

Phase 2: Triage

Bug Warning Signs in Rust

---

Phase 3: Generate Evidence

CRITICAL: Use Separate Worktree for Baseline

NEVER use git stash/git checkout to switch between baseline and optimized. This causes confusion and errors. Instead, use a separate git worktree:

Copy# One-time setup: create a baseline worktree (do this once per repo)
git worktree add ../lading-baseline main

# The baseline worktree is at ../lading-baseline
# Your optimization work stays in the current directory

For payloadtool (end-to-end):

Copy# Choose a config file (e.g., ci/fingerprints/json/lading.yaml)
CONFIG=ci/fingerprints/json/lading.yaml

# In baseline worktree
cd ../lading-baseline
cargo build --release --bin payloadtool
hyperfine --warmup 3 --runs 30 --export-json /tmp/baseline.json \
  "./target/release/payloadtool $CONFIG"
./target/release/payloadtool "$CONFIG" --memory-stats 2>&1 | tee /tmp/baseline-mem.txt

# In optimization worktree
cd /path/to/your/optimization/branch
cargo build --release --bin payloadtool
hyperfine --warmup 3 --runs 30 --export-json /tmp/optimized.json \
  "./target/release/payloadtool $CONFIG"
./target/release/payloadtool "$CONFIG" --memory-stats 2>&1 | tee /tmp/optimized-mem.txt

For inner loops (criterion):

Use cargo criterion for micro-benchmarks. Run in each worktree and compare output:

Copy# In baseline worktree
cd ../lading-baseline
cargo criterion 2>&1 | tee /tmp/criterion-baseline.log

# In optimization worktree
cd /path/to/your/optimization/branch
cargo criterion 2>&1 | tee /tmp/criterion-optimized.log

# Compare results manually - look for "change:" lines showing improvement/regression

Note: Criterion automatically compares against the last run in that worktree and reports percentage changes.

Create Benchmarks If Missing

If no benchmark exists for the changed code, create one:

Copy// In lading_payload/benches/<name>.rs
use criterion::{criterion_group, criterion_main, Criterion, Throughput};

fn benchmark_function(c: &mut Criterion) {
    let mut group = c.benchmark_group("function_name");
    group.throughput(Throughput::Bytes(1024));

    group.bench_function("baseline", |b| {
        b.iter(|| {
            function_under_test()
        })
    });

    group.finish();
}

criterion_group!(benches, benchmark_function);
criterion_main!(benches);

---

Phase 4: Validate

Decision Matrix

Verify Determinism

Determinism is verified via fingerprints. The same config (with fixed seed) must produce identical output:

CopyCONFIG=ci/fingerprints/json/lading.yaml
./target/release/payloadtool "$CONFIG" --fingerprint > /tmp/run1.txt
./target/release/payloadtool "$CONFIG" --fingerprint > /tmp/run2.txt
diff /tmp/run1.txt /tmp/run2.txt  # Must be identical

Note: Seed is specified in the config file, not as a CLI flag.

---

Phase 5: Handle Bug Discovery

If rescue uncovers a bug instead of an optimization:

Copy/lading-optimize-validate

After validation:

1. Bug recorded in validate's assets/db.yaml (via /lading-optimize-validate)
2. Record rescue as BUG_FOUND in Phase 7
3. The bug fix becomes part of rescued branch (with tests!)

---

Phase 6: Reconstruct

Copygit checkout main
git checkout -b opt/<name>-rescued

Apply only:

• KEEP changes (validated optimizations with benchmark proof)
• BUG_FOUND changes (with tests from /lading-optimize-validate)

Discard everything else.

Mandatory Before Finishing

Copyci/validate

No exceptions. Rescued branch must pass ci/validate.

---

Phase 7: Record

MANDATORY: Update db.yaml

1. Add entry to assets/db.yaml index
2. Create detailed file in assets/db/ directory

assets/db.yaml entry:

Copyentries:
  - original_branch: <opt/original-branch>
    rescued_as: <opt/original-branch-rescued>
    status: <rescued|partial|bug_found>
    file: assets/db/<branch-name>.yaml

assets/db/.yaml:

Copyoriginal_branch: <opt/original-branch>
rescued_as: <opt/original-branch-rescued>
date: <YYYY-MM-DD>
statistics:
  audited: <N>
  kept: <N>
  discarded: <N>
  bugs_found: <N>
kept_changes:
  - file: <file>
    technique: <technique>
    time: <delta>
    memory: <delta>
discarded_changes:
  - file: <file>
    reason: <reason>
bugs_found:
  - file: <file>
    validation_file: <path to validate db entry>
lessons: |
  <pattern learned>

---

Usage

Copy/lading-optimize-rescue