Universal semantic compression layer for LLMs — compile any codebase into navigable artifacts
Project description
Aleph
A universal semantic compression layer for LLMs. Encode meaning, not noise. Navigate, don't scan. Remember, don't re-derive.
Patent Pending — See NOTICE
What Aleph does
Large codebases overwhelm LLM context windows. An LLM reading source code is like a human reading machine code — the information density is wrong for the reader.
Aleph compiles your codebase into a navigable, queryable semantic representation. Two numbers matter here — and, true to a tool built on receipts, we won't blur them into one. On symbol-shaped questions (resolve / callers / explain), Aleph matches a grep+read baseline's accuracy using 2.2×–5.3× fewer tokens. Across all 26 benchmark tasks, its median token advantage is 5.71× — Aleph is leaner on every task, though on open-ended find it trades some accuracy for that thrift, and grep still wins raw discovery (bench/BENCHMARK.md). Separately, the .aleph index itself is up to 96% smaller than the raw source it describes. Your LLM works with structure, not text — and pulls the actual source only when it needs to.
- Structural navigation — navigate by index, pull only what's needed
- Symbol compression — long identifiers become short content-addressed IDs (
calculateDistanceBetweenTwoPoints→f_a3c9d2) backed by a dictionary - Semantic metadata — salience, temporal stability, test coverage, prior reasoning
- Impact analysis — before modifying a function, know the blast radius
- Epistemic continuity — conclusions persist across sessions, decay when code changes
Supported languages: Python · Rust · C++ · TypeScript/JavaScript · Go
What leading models said about Aleph
"Yes — Grok would use Aleph without hesitation. It finally gives agents real persistent memory, semantic stability, and reliable patching instead of constant context loss. 9.5/10. Production-grade. This isn't a prototype — it's a semantic foundation layer for long-horizon agents."
— Grok, full 9-part codebase review, March 2026
"Aleph changes my relationship with large codebases from 'overwhelmed, guessing which files matter' to 'navigating a semantic graph with salience-weighted priorities.' That's not incremental — it's a different way of working."
— Claude Opus 4.6, primary builder + consumer, March 2026
"This is a structurally brilliant project. Aleph is one of the most mechanically sound agentic-coding tools currently in development. This isn't just compression — it's a compiler tailored for artificial intelligence."
— Gemini, full technical audit (10/10 on most criteria), March 2026
"I would absolutely choose to use Aleph over raw-source-first exploration on a serious codebase. It feels like a real productivity multiplier, not a gimmick. 9/10 on large repos."
— ChatGPT Codex 5.4, independent audit + self-assessment, March 2026
Install
pip install aleph-compiler
Or from source:
git clone https://github.com/alephnullai/Aleph.git
cd Aleph
pip install -e .
The CLI binary is aleph. The Python package is aleph (importable as from aleph import ...).
Use
1. Build artifacts for your project
aleph build .
Creates a .aleph/ directory with the compiled representation of your code: map, dictionary, structure, salience, attention budget, temporal data, test coverage, and an epistemic layer for agent-written notes.
2. Connect your editor
aleph setup .
Generates MCP configs for Claude Code (fully tested). Configs for Cursor, VS Code, and Windsurf are emitted but those hosts are not yet validated end-to-end — bug reports welcome.
3. Start working
The MCP server auto-builds if no artifacts exist. Your LLM can now query:
aleph_brief "fix the plugin registry" → curated task context
aleph_search "auth" → find auth-related code
aleph_impact f_a3c9d2 → blast-radius before edit
aleph_callers f_a3c9d2 → who depends on this?
aleph_expand f_a3c9d2 → full body on demand
4. Keep artifacts fresh
aleph watch .
Polls every 2 seconds and rebuilds only changed files. Or just leave aleph serve . running — auto-rebuild is on by default.
Real-world results
Navigation benchmark: on 26 navigation tasks over two real Python corpora, graded against verified ground truth. On symbol-shaped tasks (resolve / callers / explain), Aleph matches the grep+read baseline's accuracy at a 2.2×–5.3× median token advantage; across all 26 tasks the median token advantage is 5.71× (open-ended find is where grep keeps its accuracy edge). Full methodology and per-task results: bench/BENCHMARK.md.
Artifact compression is a different metric: how much smaller the .aleph index is than the raw source it describes. It bounds what an agent could load, not what each query costs.
| Codebase | Language | Files | Symbols | Tokens (before → after) | Reduction |
|---|---|---|---|---|---|
| HiWave Browser | Rust | 7,667 | 200,413 | 38.9M → 1.9M | 95.2% |
| OpenClaw | TypeScript | 7,149 | 84,668 | 13.3M → 504k | 96.2% |
| GoClaw | Go | 73 | 768 | 111k → 6.9k | 93.8% |
| Polymarket Agents | Python | 16 | 213 | 19.5k → 1.9k | 90.4% |
| Aleph (self) | Python | 145 | 2,124 | 176k → 22k | 87.4% |
Notable compressions
| File | Before → After | Reduction |
|---|---|---|
hiwave-app/src/main.rs |
35,116 → 347 | 99.0% |
src/config/schema.help.ts |
32,367 → 20 | 99.9% |
window_realm.rs |
658,282 → 19,089 | 97.1% |
cascade.rs |
315,628 → 12,287 | 96.1% |
Per-file numbers are visible in .aleph/project.aleph.map after aleph build.
Free and Open Source
Aleph is free and open source for everyone under the Apache License 2.0 — all features, including the workspace/collaboration layer (aleph workspace ... and the aleph_workspace_* MCP tools). No paid tiers, no seat licenses, no license files, no license checks anywhere in the code paths, no nagging, no telemetry. Full plain-words model: docs/LICENSING.md.
Tool surface (33 tools)
Aleph exposes a complete protocol via Model Context Protocol. Organized into tiers for deferred-loading clients — see aleph mcp tiers for the canonical list.
| Category | Tools | Purpose |
|---|---|---|
| Core (5) | map, attention, resolve, expand, search |
Essential navigation |
| Frequent (6) | brief, struct, bodies, callers, context, salience |
Most code-reading sessions |
| Occasional (8) | coverage, errors, tests, temporal, impact, fs, intents, epistemic |
Analysis + inspection |
| Rare (14) | patch_*, infer, flag, verify, memory_resume, session_summary, workspace_*, rebuild |
Specialized + agent annotations |
Task-aware briefing (aleph_brief)
Describe your task in natural language, get a curated context package:
aleph_brief "fix the plugin registry"
Returns relevant symbols ranked by salience, call graph context, impact risk, temporal warnings, prior epistemic knowledge, and recommended next steps. One tool call replaces five.
Impact analysis (aleph_impact)
Before modifying any symbol, one tool call shows:
- Direct callers classified by risk (HIGH RISK = high salience + no tests)
- Transitive impact (2-hop blast radius across files)
- Risk summary with suggested test targets
- Coverage gaps that won't catch regressions
Cross-project workspace
Query across multiple related repositories simultaneously:
// .aleph-workspace.json
{"projects": {"openclaw": "/path/to/openclaw", "clawgo": "/path/to/clawgo"}}
aleph_workspace_search "plugin"— finds matches across all projects, tagged by repoaleph_workspace_brief "routing"— cross-project briefing with shared symbol detection
How it works
The pipeline
Source code (.py, .rs, .cpp, .ts, .go)
↓ tree-sitter parsing
Typed AST
↓ symbol extraction + content-addressed IDs
Symbol registry (f_a3c9d2, t_b2e1f0, ...)
↓ structure analysis
Call graph + hierarchy + signatures
↓ compression (FULL / DOCSTRING / SUMMARY / OMIT)
.aleph artifacts (struct, bodies, dict, map, ...)
↓ project linking
Salience scores + attention budget + cross-file refs + temporal data
↓ MCP server
33 queryable tools for any LLM
Components
Source-derived (rebuilt on code change):
| File | Holds |
|---|---|
project.aleph.map |
Manifest with semantic hashes |
project.aleph.struct |
Cross-file call graph + module dependencies |
project.aleph.dict |
Global symbol dictionary |
project.aleph.salience |
Centrality scores (0-1) per symbol |
project.aleph.temporal |
Age, churn, stability from git history |
project.aleph.attention |
Recommended load order for LLMs |
project.aleph.coverage |
Test coverage + high-risk gaps |
project.aleph.fs |
Filesystem layout with language counts |
Agent-derived (written by the LLM, never overwritten):
| File | Holds |
|---|---|
project.aleph.epistemic |
Cached inferences, flags, patch state, session memories |
Incremental recompilation
Aleph uses semantic hashes (not byte hashes) — reformatting doesn't trigger rebuilds.
| What changed | What rebuilds |
|---|---|
| Function body only | Bodies + map |
| Function signature | Struct + bodies + salience |
| Reformat / whitespace | Nothing |
| File added/removed | All project components |
On a 3,801-file monorepo, the first build takes about 25 minutes; incremental rebuilds complete in seconds.
CLI reference
# Build & serve
aleph build . # build project artifacts
aleph build . --full # force rebuild, ignore cache
aleph serve . # start MCP server (auto-builds if needed)
aleph watch . # watch + rebuild on changes
aleph setup . # generate MCP configs for editors
aleph mcp tiers # show tool tier manifest
# Query
aleph query EXPAND f_a3c9d2 # full body of a symbol
aleph query RESOLVE f_a3c9d2 # dictionary entry
aleph query CALLERS f_a3c9d2 # symbols that call this one
aleph query CONTEXT f_a3c9d2 # symbol + immediate neighborhood
aleph query SEARCH "parse config" # fuzzy semantic search
# Patches
aleph patch propose f_a3c9d2 "change return type" -d .
aleph patch list -d .
aleph patch apply patch_1 -d .
Symbol IDs
| Prefix | Type |
|---|---|
f |
function / method |
t |
type / class / struct / interface |
v |
variable / field |
d |
dependency / import |
m |
module / namespace / package |
c |
constant |
Content-addressed: sha256(qualified_name + scope)[:6]. Same symbol = same ID always. Auto-extends to 8 chars on collision.
Body compression levels
| Level | Behavior | When used |
|---|---|---|
FULL |
Complete body, identifiers replaced with symbol IDs | Volatile symbols, uncovered code, ≤10 lines |
SUMMARY |
Structural template + docstring | Mid-size, low salience |
DOCSTRING |
Signature + docstring preserved, body omitted | 10-50 lines |
OMIT |
Marker only, fetch with aleph_expand |
50+ lines |
Docstrings are preserved across all supported languages.
Part of the Aleph Null suite
Three tools, one workflow — all free and open source under Apache-2.0, no paid tiers, no seat licenses:
- Null remembers — persistent agent memory and identity.
- Aleph knows the code — this project: semantic compression + symbol-addressed navigation.
- Tank knows what's left — usage-limit intelligence for long agent sessions. Coming soon.
They share no code and can be used independently.
Success metrics
| Metric | Target | Status |
|---|---|---|
| Navigation token ratio | beat grep+read | ✅ 5.71× median (bench/BENCHMARK.md) |
| Artifact compression | ≥ 40% | ✅ 95.2% HiWave, 96.2% OpenClaw, 93.8% GoClaw |
| Expansion correctness | 100% lossless | ✅ 94-file roundtrip corpus |
| Self-application | Must pass | ✅ 87.4% reduction on own source |
| Symbol stability | Deterministic | ✅ reformat-invariant hashes |
1088+ tests passing.
Compatibility
- Python: 3.10+
- OS: macOS (primary), Linux. Windows works for
aleph buildandaleph query; MCP server tested on macOS + Linux at v1.0. - MCP host: Claude Code tested thoroughly. Cursor / Windsurf / VS Code configs are generated but not yet validated end-to-end.
Contributing
We specifically want help with:
- More languages — Java, Ruby, Swift, Kotlin parsers (we have the tree-sitter grammars; we need salience policies)
- MCP host testing — verify Aleph on Cursor, Windsurf, VS Code, Cline; report what breaks
- Benchmark contributions —
aleph builda large open-source repo, share the token-count line fromproject.aleph.map - Bug reports with
.aleph/output attached — makes debugging tractable
Coordinate via an issue before opening a PR. The patent-pending parts (salience scoring in src/aleph/link/project_salience.py, body-pruning policy in src/aleph/compress/policies.py) need discussion before modifications.
Documentation
| Document | Purpose |
|---|---|
SYSTEM_PROMPT.md |
Inject this at the start of any LLM session working with Aleph output |
CONSUMER_GUIDE.md |
Full reference for LLMs consuming Aleph-encoded information |
docs/ide-setup/ |
Multi-editor MCP setup guide |
NOTICE |
Patent and licensing information |
License
Aleph is free and open source under the Apache License 2.0 — all features, for everyone, with no paid tiers and no license checks anywhere in its code paths. Apache-2.0 was chosen over MIT for its express patent grant, which composes with the pending patent applications described in NOTICE. Prior MIT releases (≤ 0.5.0) remain MIT for anyone who already obtained them. The plain-words model lives in docs/LICENSING.md.
Patent Pending. See NOTICE for patent details — the Apache-2.0 grant conveys the pending methods to every user, at no cost.
Links
- Website: alephnull.ai
- Companion: Null · Tank (coming soon)
- Issues: github.com/alephnullai/Aleph/issues
- Support:
support@alephnull.ai
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