# Aleph
[](LICENSE)
[](https://www.python.org/downloads/)
[](https://pypi.org/project/aleph-rlm/)
Aleph is an [MCP server](https://modelcontextprotocol.io/) plus companion skill
workflow (`/aleph` in Claude Code, `$aleph` in Codex CLI) for recursive LLM work.
It stores working data in a Python process and exposes tools so the model can
retrieve slices, run code, and iterate without repeatedly injecting full files
into prompt context.
Core capabilities:
- Load large files and codebases into process memory
- Search and inspect targeted ranges (`search_context`, `peek_context`)
- Run computation over context with `exec_python`
- Orchestrate recursive sub-queries and recipe pipelines
- Save and restore sessions for long investigations
Design is based on the
[Recursive Language Model](https://arxiv.org/abs/2512.24601) (RLM) architecture.
```text
+-----------------+ tool calls +--------------------------+
| LLM client | ---------------> | Aleph (Python process) |
| (context budget)| <--------------- | search / peek / exec |
+-----------------+ small results +--------------------------+
```
## Quick Start
1. Install:
```bash
pip install "aleph-rlm[mcp]"
```
2. Auto-configure your MCP client:
```bash
aleph-rlm install
```
3. Verify Aleph is reachable in your assistant:
```text
get_status()
# or
list_contexts()
```
4. Run the skill flow on a real file:
```bash
/aleph path/to/large_file.log
# or in Codex CLI
$aleph path/to/large_file.log
```
Expected behavior: Aleph loads the file into process memory, then begins
analysis with tool calls (`search_context`, `peek_context`, `exec_python`)
without requesting pasted raw content.
## Common Workloads
| Scenario | What Aleph Does |
|---|---|
| Large log analysis | Load large logs, trace patterns, correlate events |
| Codebase navigation | Search symbols, inspect routes, trace behavior |
| Data exploration | Analyze JSON/CSV exports with Python helpers |
| Mixed document ingestion | Load PDFs, Word docs, HTML, and compressed logs |
| Semantic retrieval | Use semantic search, then zoom with line/char peeks |
| Long investigations | Save sessions and resume from memory packs |
## Commands
Installing `aleph-rlm` gives you three commands:
| Command | Purpose |
|---|---|
| `aleph` | MCP server (also supports `run` / `shell`) |
| `aleph-rlm` | Installer/config helper (also supports `run` / `shell`) |
| `alef` | Legacy standalone CLI (deprecated) |
How to think about it:
- Run `aleph-rlm install` once to configure clients.
- MCP clients should run `aleph` as the server command.
- Use `aleph run` (or `aleph-rlm run`) for terminal-only mode.
## MCP Mode
### Automatic Setup
```bash
aleph-rlm install
```
To customize workspace scope, backend, docs mode, or Docker settings:
```bash
aleph-rlm configure
```
### Manual Setup (Any MCP Client)
Use this as a practical default:
```json
{
"mcpServers": {
"aleph": {
"command": "aleph",
"args": ["--enable-actions", "--workspace-mode", "any", "--tool-docs", "concise"]
}
}
}
```
### Verify MCP Wiring
In your assistant session:
```text
get_status()
```
If your client namespaces tools, use `mcp__aleph__get_status`.
### Config File Locations
| Client | macOS/Linux | Windows |
|---|---|---|
| Claude Code | `~/.claude/settings.json` | `%USERPROFILE%\.claude\settings.json` |
| Claude Desktop | `~/Library/Application Support/Claude/claude_desktop_config.json` | `%APPDATA%\Claude\claude_desktop_config.json` |
| Cursor | `~/.cursor/mcp.json` | `%USERPROFILE%\.cursor\mcp.json` |
| VS Code | `~/.vscode/mcp.json` | `%USERPROFILE%\.vscode\mcp.json` |
| Codex CLI | `~/.codex/config.toml` | `%USERPROFILE%\.codex\config.toml` |
More per-client setup details are in [MCP_SETUP.md](MCP_SETUP.md).
## The `/aleph` and `$aleph` Skill
For skill-based usage, configure both:
1. MCP server configured in the client
2. Skill prompt installed (`docs/prompts/aleph.md`)
### Invocation
| Client | Skill command | Typical usage |
|---|---|---|
| Claude Code | `/aleph` | `/aleph path/to/file` |
| Codex CLI | `$aleph` | `$aleph path/to/file` |
### Skill Install Paths
Download [`docs/prompts/aleph.md`](docs/prompts/aleph.md) and place it at:
- Claude Code: `~/.claude/commands/aleph.md`
- Codex CLI: `~/.codex/skills/aleph/SKILL.md`
Windows equivalents:
- `%USERPROFILE%\.claude\commands\aleph.md`
- `%USERPROFILE%\.codex\skills\aleph\SKILL.md`
### Quick Behavior Check
Use this exact prompt:
```text
$aleph path/to/large_file.log
Then call list_contexts() and show the loaded context_id before analysis.
```
Healthy behavior:
1. Tool call to `load_file(path=...)`
2. Context appears in `list_contexts()`
3. Follow-up search/peek/exec on that context
## Core Workflow Patterns
### 1) Load File -> Work Immediately
```python
load_file(path="/absolute/path/to/large_file.log", context_id="doc")
search_context(pattern="ERROR|WARN", context_id="doc")
peek_context(start=1, end=60, unit="lines", context_id="doc")
exec_python(code="print(line_count())", context_id="doc")
finalize(answer="Summary...", context_id="doc")
```
Note: with MCP action tools, absolute paths are safest for `load_file`.
### 2) Analyze Raw Text
```python
load_context(content=data_text, context_id="doc")
search_context(pattern="keyword", context_id="doc")
finalize(answer="Found X at line Y", context_id="doc")
```
### 3) Recipe Pipelines
Recommended sequence:
```text
validate_recipe -> estimate_recipe -> run_recipe
```
Example:
```python
run_recipe(recipe={
"version": "aleph.recipe.v1",
"context_id": "doc",
"budget": {"max_steps": 6, "max_sub_queries": 5},
"steps": [
{"op": "search", "pattern": "ERROR|WARN", "max_results": 10},
{"op": "map_sub_query", "prompt": "Root cause?", "context_field": "context"},
{"op": "aggregate", "prompt": "Top causes with evidence"},
{"op": "finalize"}
]
})
```
### 4) Sub-Query Batching (Important)
Prefer fewer large sub-query calls over many tiny calls.
- Bad: 1000 calls of 1K chars
- Good: 5-10 calls of about 100K to 200K chars
```python
exec_python(code="""
chunks = chunk(100000)
summaries = sub_query_batch("Summarize this chunk:", chunks)
print(summaries)
""", context_id="doc")
```
### 5) Save and Resume
```python
save_session(context_id="doc", path=".aleph/session_doc.json")
load_session(path=".aleph/session_doc.json")
```
## CLI Mode (Standalone)
Use this when you want Aleph without MCP integration.
```bash
# Basic
aleph run "What is 2+2?" --provider cli --model claude
# With file context
aleph run "Summarize this log" --provider cli --model claude --context-file app.log
# JSON output with trajectory
aleph run "Analyze" --provider cli --model claude --context-file data.json --json --include-trajectory
```
### Common Flags
| Flag | Description |
|---|---|
| `--provider cli` | Use local CLI tools instead of API provider |
| `--model claude|codex|gemini` | CLI backend to use |
| `--context-file <path>` | Load context from file |
| `--context-stdin` | Read context from stdin |
| `--json` | Emit JSON output |
| `--include-trajectory` | Include full reasoning trace |
| `--max-iterations N` | Limit loop steps |
### Common Environment Variables
| Variable | Description |
|---|---|
| `ALEPH_SUB_QUERY_BACKEND` | `auto`, `codex`, `gemini`, `claude`, or `api` |
| `ALEPH_SUB_QUERY_TIMEOUT` | Sub-query timeout in seconds |
| `ALEPH_SUB_QUERY_SHARE_SESSION` | Share MCP session with CLI sub-agents |
| `ALEPH_CLI_TIMEOUT` | Timeout for CLI calls |
## Tool Overview
### Core Tools (Always Available)
| Category | Tools |
|---|---|
| Context | `load_context`, `list_contexts`, `diff_contexts` |
| Search | `search_context`, `semantic_search`, `peek_context`, `chunk_context` |
| Compute | `exec_python`, `get_variable` |
| Reasoning | `think`, `evaluate_progress`, `summarize_so_far`, `get_evidence`, `finalize` |
| Runtime Config | `configure` |
| Recipes | `validate_recipe`, `estimate_recipe`, `run_recipe`, `compile_recipe`, `run_recipe_code` |
### Action Tools (`--enable-actions`)
| Category | Tools |
|---|---|
| Filesystem | `load_file`, `read_file`, `write_file` |
| Shell | `run_command`, `run_tests`, `rg_search` |
| Persistence | `save_session`, `load_session` |
| Remote MCP | `add_remote_server`, `list_remote_servers`, `list_remote_tools`, `call_remote_tool`, `close_remote_server` |
`exec_python` includes 100+ helpers (`search`, `chunk`, `lines`, `extract_*`,
`sub_query`, `sub_query_batch`, `sub_query_map`, `sub_aleph`, Recipe DSL helpers,
and more). Recursion helpers are available inside `exec_python`, not as top-level
MCP tools.
## Swarm Mode (Optional)
Aleph can act as shared memory for multiple agents.
```text
Agent A/B/C <-> Aleph contexts in shared RAM
```
Simple pattern:
1. Shared KB context: `swarm-<name>-kb`
2. Task contexts: `task-<id>-spec`, `task-<id>-findings`
3. Agent-private contexts: `<agent>-workspace`
Example write/read:
```python
exec_python(code="ctx_append('Auth uses JWT with RS256')", context_id="task-42-findings")
search_context(pattern="JWT", context_id="task-42-findings")
```
## Context Isolation and Safety
Aleph enforces strict boundaries to prevent raw context from leaking into
the LLM's context window:
- **System prompt isolation.** The default system prompt does not include a
raw context preview. The placeholder is replaced with
`[OMITTED FOR CONTEXT ISOLATION]`.
- **`get_variable("ctx")` is policy-aware.** In `isolated` policy, retrieving
`ctx` via the MCP boundary is blocked with guidance. In `trusted` policy, it
is allowed but still subject to response caps/truncation. Prefer processing
data inside `exec_python` and retrieving compact derived results with
`get_variable`.
- **Execution output truncation.** `exec_python` stdout, stderr, and return
values are all truncated to `max_output_chars` (default 50,000). The MCP
tool response is further capped at `max_tool_response_chars` (default
10,000). Both limits are configurable.
- **Tool response caps.** Every MCP tool response (peek, search, semantic
search, get_variable, etc.) is bounded by the same response-size cap.
### Deployment Profiles
Set `ALEPH_CONTEXT_POLICY` to choose a profile:
| Profile | Behavior |
|---|---|
| `trusted` (default) | Low friction. Auto memory-pack, session save/load without confirmation. |
| `isolated` | Explicit consent. Requires `confirm=true` for session export/import, disables auto memory-pack. Blocked tools return actionable alternatives. |
Switch at runtime with `configure(context_policy="isolated")`. See
[CONFIGURATION.md](docs/CONFIGURATION.md#deployment-profiles) for details.
### Safe Usage Pattern
```python
# Compute server-side — data stays in Aleph RAM
exec_python(code="""
errors = [l for l in ctx.splitlines() if 'error' in l.lower()]
result = f'Found {len(errors)} errors. First 3: {errors[:3]}'
""", context_id="doc")
# Retrieve only the small derived result
get_variable(name="result", context_id="doc")
```
Avoid returning full-context payloads unless necessary. In `isolated` policy,
`get_variable("ctx")` is blocked; in `trusted` policy large raw responses are
still truncated by output caps.
## Configuration Quick Reference
### Workspace and Safety
| Flag/Variable | Purpose |
|---|---|
| `--workspace-root <path>` | Root for relative action paths |
| `--workspace-mode <fixed|git|any>` | Path access policy |
| `--require-confirmation` | Require `confirm=true` for actions |
| `ALEPH_WORKSPACE_ROOT` | Override workspace root |
| `ALEPH_CONTEXT_POLICY` | `trusted` (default) or `isolated` |
| `ALEPH_OUTPUT_FEEDBACK` | `full` (default) or `metadata` |
| `ALEPH_MAX_RECIPE_CONCURRENCY` | Max parallel `map_sub_query` tasks (default `10`) |
### Limits
| Flag | Default | Purpose |
|---|---|---|
| `--max-file-size` | 1 GB | Max file read size |
| `--max-write-bytes` | 100 MB | Max file write size |
| `--timeout` | 180 s | Sandbox/command timeout |
| `--max-output` | 50,000 chars | Max command output |
| `ALEPH_MAX_TOOL_RESPONSE_CHARS` | 10,000 chars | MCP tool response cap |
### Recursion Budgets
| Variable | Default | Purpose |
|---|---|---|
| `ALEPH_MAX_DEPTH` | 2 | Max `sub_aleph` nesting depth |
| `ALEPH_MAX_ITERATIONS` | 100 | Total RLM steps |
| `ALEPH_MAX_WALL_TIME` | 300 s | Wall-time cap |
| `ALEPH_MAX_SUB_QUERIES` | 100 | Max `sub_query` calls |
| `ALEPH_MAX_TOKENS` | unset | Optional per-call output cap |
Full configuration details: [docs/CONFIGURATION.md](docs/CONFIGURATION.md)
## Troubleshooting
- Tool not found: ensure Aleph MCP server is running.
- Context not found: verify `context_id` and check `list_contexts()`.
- No search hits: broaden regex or use `semantic_search`.
- `rg_search` is slow: install ripgrep (`rg`).
- Running out of context: use `summarize_so_far()`.
- Session load errors: check file path and memory pack schema.
## Documentation
| Document | Purpose |
|---|---|
| [MCP_SETUP.md](MCP_SETUP.md) | Client-by-client MCP configuration |
| [docs/CONFIGURATION.md](docs/CONFIGURATION.md) | Full flags and environment variables |
| [docs/langgraph-rlm-default.md](docs/langgraph-rlm-default.md) | LangGraph integration with RLM-default tool usage |
| [examples/langgraph_rlm_repo_improver.py](examples/langgraph_rlm_repo_improver.py) | Repo-improvement runner with optional LangSmith tracing |
| [docs/prompts/aleph.md](docs/prompts/aleph.md) | Skill workflow and tool reference |
| [CHANGELOG.md](CHANGELOG.md) | Release history |
| [DEVELOPMENT.md](DEVELOPMENT.md) | Contributor guide |
## Development
```bash
git clone https://github.com/Hmbown/aleph.git
cd aleph
pip install -e ".[dev,mcp]"
pytest tests/ -v
ruff check aleph/ tests/
```
## References
- Zhang, A. L., Kraska, T., Khattab, O. (2025)
[Recursive Language Models (arXiv:2512.24601)](https://arxiv.org/abs/2512.24601)
## License
MIT
