Epistle 📜

Pack a codebase into a single, LLM-friendly context file — with compression, token budgets, git awareness, and secret redaction built in.

Epistle scans a project (or a remote repo), filters out noise, redacts credentials, shapes the content to fit your model's context window, and emits one tidy file in Markdown, XML, plain text, or JSON.

npx epistle --stdout | pbcopy         # pack the current directory
npx epistle src lib --compress -o ctx.md
npx epistle yamadashy/repomix --fit   # pack a remote repo by shorthand

Fast on real repos: packing facebook/react (7,000+ files) takes ~5s.

Why Epistle?

Every codebase-packing tool solves part of the problem. Epistle combines the best ideas from the whole field — and adds a few of its own:

Capability	Epistle	repomix	code2prompt	gitingest	files-to-prompt	yek
Markdown / XML / plain / JSON output	✅	✅	template	❌	partial	template
Fence-safe Markdown (files containing ```)	✅	❌	❌	❌	✅	—
Signature compression (AST, tree-sitter)	✅ +heuristic fallback	✅	❌	❌	❌	❌
Comment / blank-line stripping	✅	✅	❌	❌	❌	❌
Fit-to-budget file dropping	✅	❌ (fails)	❌	❌	❌	✅
Changed-files-only pack (--diff)	✅	❌	❌	❌	❌	❌
Git churn ordering (important last)	✅	partial	❌	❌	❌	✅
Secret redaction (default ON)	✅	✅ scan	❌	❌	❌	❌
Credential-file exclusion (.env, keys)	✅	✅	❌	❌	❌	❌
Context-window fit report (--fit)	✅	❌	❌	❌	❌	❌
Remote repo ingest (owner/repo)	✅	✅	❌	✅	❌	❌
MCP server mode (--mcp)	✅	✅	✅	❌	❌	❌
Shell completions	✅ bash/zsh/fish	✅	❌	❌	❌	❌
Personas + prompt recipes	✅	❌	templates	❌	❌	❌
Named config profiles (--profile)	✅	❌	❌	❌	❌	❌
Config file JSON Schema	✅	✅	❌	❌	❌	❌
stdin file lists (`find …	epistle --stdin`)	✅	✅	❌	❌	✅

(See docs/RESEARCH.md for the full competitive analysis.)

Install

npm install -g epistle    # or: npx epistle

Requires Node.js ≥ 18.

Quickstart

epistle -o context.md                 # pack cwd into context.md
epistle src test -o ctx.md            # only these paths
epistle --dry-run                     # preview files + token counts, write nothing
epistle --stdout | llm "explain this" # pipe into anything
epistle --copy                        # straight to clipboard

Fitting big codebases into small windows

epistle --compress -o ctx.md          # keep signatures, elide bodies (~80% smaller)
epistle --remove-comments --remove-empty-lines -o ctx.md
epistle --max-tokens 100000 -o ctx.md # drop heaviest files until it fits
epistle --lite -o ctx.md              # prune styles, images, data files
epistle --fit                         # bar chart: % of Claude/GPT/Gemini windows used (estimated)
epistle --hog-depth auto              # find your token hogs

--max-file-size <kb> caps individual files (default 100KB). Binary files are always listed but never inlined.

--compress uses real parse trees (tree-sitter) for TypeScript, JSX, Python, Go, and Rust, so multi-line signatures, decorators, and return types survive intact. Other languages fall back to a fast line-based heuristic. The tree-sitter grammars are an optional dependency (~55MB) — if omitted or installed without optional dependencies, Epistle seamlessly falls back to the fast line-based heuristic for all languages without error.

Git awareness

epistle --diff -o review.md           # ONLY files changed vs HEAD (incl. untracked)
epistle --diff main -o pr.md          # ... or vs any ref
epistle --include-diffs --include-logs 10 -o ctx.md
epistle --sort churn                  # most-edited files last (LLMs read the end best)
epistle user/repo                     # shallow-clone + pack a remote repo (shorthand)
epistle --remote https://github.com/x/y.git --remote-branch dev

A lone owner/repo argument that doesn't exist as a local path is packed as a remote repository — no --remote flag needed. A local path of the same name always wins.

Security

Secret redaction is on by default: OpenAI/Anthropic/GitHub/GitLab/ Slack/Stripe/npm/Hugging Face/SendGrid/Twilio token shapes, JWTs, PEM private-key blocks, and apiKey = "…" assignments are replaced with [REDACTED_SECRET]. Credential-shaped files (.env*, SSH keys, .pem, .npmrc, service-account JSON…) are excluded entirely and reported.

epistle --no-redact                   # opt out (output carries a warning)

Prompt engineering built in

epistle --persona architect           # system-style header (arch|sec|ref aliases)
epistle --recipe review               # curated prompts: review | test | refactor
                                      #   | onboard | document | audit
epistle -t "Focus on the scheduler"   # your own task, composable with recipes

Output formats

epistle --format markdown             # default: tree + ToC + fenced files
epistle --format xml                  # CDATA-wrapped, Claude-friendly
epistle --format plain                # separator-delimited text
epistle --format json                 # machine-readable, per-file tokens
epistle --tree-only                   # just the directory tree
epistle -n                            # line numbers
epistle --encoding cl100k_base        # GPT-3.5/4-era token counts

Filtering

Ignore sources, in order: built-in defaults (lockfiles, node_modules, build dirs, binaries…) → root .gitignore → nested .gitignores → .llmignore → .epistleignore → config exclude → --exclude. --include force-includes after all filtering.

epistle -e "**/*.test.ts" "fixtures/**" -i "dist/types.d.ts"
find . -name "*.py" -newer main.py | epistle --stdin
git ls-files -z src | epistle --stdin -0

Configuration

epistle --init                        # writes epistle.config.json

The generated file carries a "$schema" reference, so editors autocomplete and validate it; Epistle also validates it at load time with field-level errors.

{
  "$schema": "https://unpkg.com/epistle/epistle.schema.json",
  "output": { "file": "context.md", "format": "markdown", "lineNumbers": false, "copy": false },
  "exclude": ["**/*.snap"],
  "maxFileSizeKB": 100,
  "compress": false,
  "removeComments": false,
  "maxTokens": 150000,
  "sort": "churn",
  "includeLogs": 10,
  "profiles": {
    "pr-review": { "includeDiffs": true, "sort": "churn" },
    "tiny": { "compress": true, "removeComments": true, "maxTokens": 30000 }
  }
}

CLI flags always override config. Select a profile with epistle --profile tiny.

Console UX

• All diagnostics go to stderr; the pack itself is the only thing on stdout, so piping is always safe.
• -q/--quiet for errors-only, --verbose for scan details and timings.
• Banner/spinner only on interactive terminals; NO_COLOR respected.
• After each pack: token-colored dashboard, top context hogs (--hog-depth 0|N|auto), and --fit context-window bars.

MCP server mode

Expose Epistle's pack pipeline to agentic MCP clients (Claude Code, Cursor, …) over stdio:

epistle --mcp

Tools: pack_codebase (local dir, with compression / diff-vs-ref / token budgets / git history), pack_remote (shallow-clone owner/repo), read_output (page a pack by line range), grep_output (regex search a pack). Packs are stored server-side and addressed by ID, so only bounded summaries, chunks, and matches cross the protocol — a multi-megabyte pack costs the client a few hundred tokens until it asks for content.

Example client config:

{ "mcpServers": { "epistle": { "command": "epistle", "args": ["--mcp"] } } }

Shell completions

epistle completion bash > /etc/bash_completion.d/epistle
epistle completion zsh  > "${fpath[1]}/_epistle"
epistle completion fish > ~/.config/fish/completions/epistle.fish

Flags, formats, and recipes complete out of the box; --profile completes dynamically from the profiles in your epistle.config.json.

All options

Run epistle --help for the complete list.

License

MIT — see LICENSE.