Compressing onboarding files

Instruction files load every session, so every saved token compounds. Compress prose aggressively while never touching the technical payload - and never trading away clarity where ambiguity is dangerous.

Announce at start: "Using compress-onboarding on <file> at level <level>."

Usage: compress-onboarding <file> [--level off|lite|full|ultra] Default file: the repo's AGENTS.md. Works under any SKILL.md-compatible runtime.

Levels (sticky per repo)

Resolve the level from --level if given, else .aiboarding/config.json: compression_level, else full. When --level is given, persist it back to config.json - the level is a per-repo decision, not per-run.

• off - no rewriting. Still run the size report (step 5) so bloat is visible.
• lite - remove filler, pleasantries, hedging, and restatement. Full sentences

kept. ("In order to build the project, you should run…" → "To build, run…")

• full (default) - additionally drop articles, compress to fragments and

short synonyms, allow X → Y notation. ("The dev server can be started with npm run dev" → "Dev server: npm run dev.")

• ultra - telegraphic; every non-load-bearing word goes. Only for repos

pressed against the 32 KiB Codex cap; confirm with the user before first use.

Byte-preservation invariants (hard guarantees)

Compression must NEVER alter: fenced code blocks (including the fence lines), inline backtick spans, shell commands, URLs, file paths, identifiers and symbol names, quoted error strings, <!-- aiboarding-* --> markers, YAML frontmatter, and table structure. If a protected span is wrong, fixing it is an update, not a compression - route it through update-agent-onboarding.

While rewriting, keep commands/identifiers/paths/error strings backtick-quoted (add backticks where the source lacks them - adding protection is allowed; removing it is not). The checker treats backtick spans as protected.

Auto-clarity exemptions

Never compress below full sentences, regardless of level:

• Agent Guardrails and Escalation - Ask the User When sections: cap at lite.

A misread guardrail costs more than its tokens.

• Security warnings and destructive/irreversible-action instructions.
• Multi-step sequences where fragment order creates ambiguity ("migrate table drop

column backup first" - unclear; keep explicit ordering words).

Procedure

1. Snapshot. Copy the target file to a temp path (before).
2. Compress section by section at the resolved level, honoring the invariants

and exemptions above.

1. Verify. Run .aiboarding/tools/check-preservation <before> <after> (fall

back to the plugin's templates/tools/check-preservation if not installed). Fix every reported span and re-run until clean. Never hand-wave this step.

1. Approval gate. Show the user a diff of the compressed file against the

original. Write only after approval.

1. Receipt. Measure before/after: exact bytes and lines always; token counts

with a real tokenizer if one is available in the environment (e.g. Python tiktoken), otherwise tokens_approx = bytes / 4, explicitly labeled approximate. Append to .aiboarding/state.json:receipts (one object per line, keeping the file hook-readable): json { "file": "AGENTS.md", "level": "full", "bytes_before": 8123, "bytes_after": 4310, "lines_before": 190, "lines_after": 121, "tokens_before_approx": 2031, "tokens_after_approx": 1078, "measured_at": "2026-07-02" } Report the saving to the user; since the file loads every session, note the per-session saving - never claim unlabeled exact token numbers without a real tokenizer.

1. Size check. Run .aiboarding/tools/check-size-budget <file>; if it still

WARNs after full, suggest moving detail to .claude/rules/ or nested AGENTS.md files rather than jumping to ultra.

Writing into shared files

When compression output must land inside a file that also has user-owned content (e.g. a hand-written CLAUDE.md), write only within the aiboarding marker fence via .aiboarding/tools/inject-fenced - re-runs stay idempotent and uninstall stays clean.