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Show HN: ContextForge – context engineering platform for AI-assisted development

ContextForge, a pre-alpha context engineering platform for AI-assisted development, released version 0.4.2 as its first public-release candidate. The tool scans local repositories to build deterministic structural maps, supports bounded task-aware discovery, and exports portable context packages and handoffs, without editing source code or executing arbitrary commands. It requires Python 3.12 or newer and is available via PyPI as contextforge-repo.

read9 min views4 publishedAug 21, 2026
Show HN: ContextForge – context engineering platform for AI-assisted development
Image: Michielbdejong (auto-discovered)

Build bounded, reviewable repository context for coding agents.

ContextForge scans local repositories, builds deterministic structural maps, supports bounded task-aware discovery, and produces portable context packages and handoffs. It helps you decide what an external coding agent should see without giving ContextForge permission to edit source code or run arbitrary commands.

Quick start · CLI · Configuration · Wiki · Discussions · Contribution policy

Important

ContextForge is pre-alpha software. Version 0.4.2

is the first public-release candidate. Discovery benchmarking is experimental and its results should be reviewed alongside the recorded provider, model, configuration, and source snapshot.

Deterministic repository inventory. Scan files with stable ordering, portable paths, hashes, language classification, ignore rules, and bounded reads.Reviewable selection. Choose exact files, directories, GitWildMatch patterns, or line ranges—or ask a configured model for a bounded suggestion.Local repository intelligence. Store immutable structural and optional semantic index generations under.contextforge/index

.Portable artifacts. Export Markdown or JSON context packages, JSON task handoffs, and compiled Markdown prompts.Explicit trust boundaries. ContextForge does not edit repository source, execute repository code, expose shell tools, or mutate Git state.Automation-friendly output. Structured results stay on stdout while progress and diagnostics stay on stderr.

flowchart LR
    R["Repository"] --> S["scan / index"]
    S --> D["task-aware discovery"]
    D --> B["bounded selection"]
    B --> P["context package"]
    P --> A["external coding agent"]

A model is optional for scanning, trees, manual context packages, and structural-only indexing:

contextforge scan .
contextforge index build . --provider none
contextforge context create . \
  --include pyproject.toml \
  --directory src/contextforge/context \
  --exclude "**/__init__.py" \
  --format markdown \
  --output context.md

ContextForge requires Python 3.12 or newer. Install the published distribution:

python -m pip install contextforge-repo

For an isolated command-line installation, use either tool manager:

pipx install contextforge-repo
uv tool install contextforge-repo

The PyPI distribution is named contextforge-repo

; the import package remains contextforge

, and the installed commands remain contextforge

and ctxf

. The similarly named context-forge-cli

distribution is a different, unaffiliated project.

To install a checked-out source tree instead:

git clone https://github.com/waterflane/ContextForge.git
cd ContextForge
python -m venv .venv
source .venv/bin/activate
python -m pip install --upgrade pip
python -m pip install .

Windows PowerShell:

git clone https://github.com/waterflane/ContextForge.git
Set-Location ContextForge
python -m venv .venv
.\.venv\Scripts\Activate.ps1
python -m pip install --upgrade pip
python -m pip install .

The installation provides equivalent contextforge

and ctxf

console commands. python -m contextforge

is also supported.

Inspect a repository without writing ContextForge state:

contextforge scan .
contextforge tree . --depth 2
contextforge context create . `
  --include 'pyproject.toml' `
  --directory 'src/contextforge/context' `
  --exclude '**/__init__.py' `
  --format json `
  --output 'context.json'
contextforge context inspect 'context.json'

Build a structural-only local index and inspect its status:

contextforge index build . --provider none
contextforge index status .

Tip

Start with manual context creation when you already know the relevant files. Use discovery when the task spans unfamiliar code and you have configured a supported model provider.

  • create a compact review packet for an external coding agent;
  • map a repository without sending source to a model;
  • inspect stale, missing, or failed index records;
  • discover likely entry points, tests, configuration, and dependencies for a task;
  • preserve a validated handoff that can be reviewed without the original checkout;
  • benchmark discovery quality and repeatability against versioned manifests.

Every command supports --help

; run group help before using advanced or mutating operations.

Command Behavior State
contextforge version
Print the installed version Read-only
contextforge doctor
Report basic installation settings Read-only
contextforge scan [PATH]
Inventory repository files Read-only unless --output is used
contextforge tree [PATH]
Render a project tree Read-only unless --output is used
contextforge context suggest [PATH]
Suggest task-relevant context Source/index read-only; records a safe run summary
contextforge context create [PATH]
Build a manual package or automatic handoff Reads source; optional artifact writes
contextforge context inspect PACKAGE
Validate a JSON context package offline Read-only
contextforge context review PACKAGE
Review a JSON task handoff offline Read-only
contextforge index build [PATH]
Publish a new local index generation Mutates .contextforge/index
contextforge index update [PATH]
Increment an existing index Mutates .contextforge/index
contextforge index status [PATH]
Inspect source/index drift and lock state Read-only
contextforge index clean [PATH]
Delete generated index data Destructive to index data only
contextforge diagnostics last [PATH]
Show the latest safe run summary Read-only
contextforge diagnostics show PATH ID
Show one safe run summary Read-only
contextforge diagnostics config [PATH]
Explain effective configuration Read-only
contextforge diagnostics provider [PATH]
Show provider policy without probing it Read-only
contextforge mcp serve [PATH]
Run the local read-only stdio MCP server Read-only session
contextforge benchmark discovery PATH
Run manifest-driven discovery benchmarks Repository/index read-only; experimental

Global diagnostic options are --log-level

, --log-format

, --log-file

, repeatable --log-component

, --no-log-file

, --no-color

, and -v

/-vv

. Detailed syntax, defaults, streams, side effects, mistakes, and examples are in the Wiki CLI reference.

Project configuration is closed, versioned TOML. Resolution order is:

  • command-line option;
  • supported CONTEXTFORGE_*

environment variable; .contextforge/config.local.toml

;.contextforge/config.toml

, or an explicit--config PATH

;- built-in default.

The primary supported environment variables are:

CONTEXTFORGE_MODEL_CONTEXT_WINDOW

;CONTEXTFORGE_MODEL_CONNECT_TIMEOUT

;CONTEXTFORGE_MODEL_READ_TIMEOUT

;CONTEXTFORGE_MODEL_OPERATION_TIMEOUT

;CONTEXTFORGE_JSON_REPAIR_ATTEMPTS

;CONTEXTFORGE_LOG_LEVEL

,CONTEXTFORGE_LOG_FORMAT

,CONTEXTFORGE_LOG_FILE

, andCONTEXTFORGE_LOG_COMPONENTS

.

The default provider is local Ollama at http://127.0.0.1:11434/api/chat

using model qwen2.5-coder:7b

. Use --provider none

for structural-only indexing. The openai-compatible

provider and its lmstudio

CLI alias require an exact model ID and a suitable base_url

.

Model-backed discovery requires the configured provider to be running with the named model available. ContextForge's configured context_window

must not exceed the window actually loaded by that provider; inspect the resolved policy before a long run with contextforge diagnostics provider PATH

.

Credential configuration stores only the name of an environment variable in credential_env

; the credential value is resolved at request time. See the configuration guide and Wiki configuration reference.

Fresh builds current structural evidence in memory and does not load persisted semantic records or repository maps.Indexed requires a readable active index and uses current indexed structure, semantics, and maps.Hybrid is the default. It starts with current index evidence, fills structural gaps from the live snapshot, and explicitly falls back to fresh structure when no valid index exists.

All successful selections are verified against current source identities. Model-backed runs can produce different valid selections; ContextForge claims deterministic rendering for the same validated result, not deterministic model behavior. See Discovery output and benchmarks.

Manual packages use explicit selectors. With no include selector, all selectable snapshot files are included up to the configured limits:

contextforge context create . --include README.md --format markdown
contextforge context create . --directory src --exclude "**/__init__.py"
contextforge context create . --glob "tests/test_*.py" --no-include-tree
contextforge context create . \
  --include pyproject.toml \
  --include-lines pyproject.toml:1-24 \
  --format json

Automatic mode requires a non-empty task and does not accept manual directory, glob, or line-range selectors:

contextforge context suggest . \
  --task "Trace configuration precedence" \
  --discovery hybrid \
  --format markdown

contextforge context create . \
  --task "Trace configuration precedence" \
  --discovery hybrid \
  --git-diff working \
  --format json \
  --output handoff.json \
  --prompt-output prompt.md

context suggest

does not write source or index state, but current diagnostics policy may write a safe summary under .contextforge/runs

. Output artifacts are written atomically; existing destinations require --force

where that option is available.

Note

benchmark discovery

is experimental in 0.4.2

; model-backed repeatability measurements are observations for the recorded fixture state, not guarantees. Start the configured provider first and use the same context-window value in ContextForge and the provider runtime.

contextforge benchmark discovery 'C:\Repositories' `
  --tasks '.\benchmarks\discovery.json' `
  --modes 'fresh,indexed,hybrid' `
  --repeat 3 `
  --format json `
  --output '.\benchmark-report.json'

The runner is repository/index read-only, disables configured file logging, and records complete, failed, and cancelled runs in the result. Exit code 3

means the command produced a complete benchmark report containing at least one task, expectation, or budget failure. Do not discard stdout or the requested output file when handling that code. Every run remains bounded by manifest limits, provider retry limits, operation timeouts, and the configured context window.

  • scans: table

,json

; - trees: text

,markdown

,json

; - suggestions: text

, compatibility aliastable

,markdown

,json

; - context packages: markdown

,json

; - index status and diagnostics: table

,json

; - discovery benchmarks: text

,markdown

,json

.

When no output path is supplied, the selected result is written to stdout. Progress, logs, and errors use stderr, preserving parseable JSON stdout. Some commands print a confirmation to stdout after writing a file; benchmark output files are the exception and leave stdout empty.

Common process exit codes are 0

for success, 1

for operational failure, 2

for invalid usage or configuration, and 130

for cancellation. Exit code 3

has command-specific meaning: unreadable entries with scan --fail-on-error

, or a completed discovery benchmark with regression failures.

ContextForge is a typed Python modular monolith. Core application and domain logic remain independent from Typer, FastAPI, model-provider implementations, storage adapters, and future editor integrations. The scanner creates a verified snapshot; intelligence extracts structural facts and optional semantic interpretations; discovery selects bounded candidates; context and handoff modules materialize portable artifacts; CLI, HTTP, and MCP are thin interfaces.

Read the architecture overview for dependency boundaries and the security policy for trust and path-safety details.

CLI logging and diagnosticsConfigurationDiscovery and benchmarkingDevelopmentTroubleshootingArchitecture notesComplete GitHub Wiki

The Wiki is maintained in its separate GitHub Wiki repository. A prepared local wiki/

workspace is intentionally ignored by the main repository.

python -m venv .venv
.\.venv\Scripts\Activate.ps1
python -m pip install --upgrade pip
python -m pip install -e ".[dev]"
python -m ruff check .
python -m mypy src
python -m pytest

Build validation and owner-only publication steps are in the release checklist. Release publication is an owner-triggered workflow protected by GitHub environments and PyPI OIDC.

ContextForge is pre-alpha and under active solo-maintainer development. Manual scanning, trees, context packages, local indexing, diagnostics, and read-only MCP are implemented. Model-assisted discovery depends on the configured provider and its structured-output behavior. Remote MCP transport, autonomous source edits, shell/process tools, embeddings, IDE extensions, and coding-agent orchestration are not implemented.

Use the Q&A category in GitHub Discussions for usage and support questions. Use GitHub Issues for reproducible bugs and focused feature suggestions. Do not post secrets, repository source, full prompts, or private logs in either place.

External contributions are welcome through a fork and pull request into dev

. Discuss large changes in an Issue before implementation. Merges require owner approval and passing CI; contributors do not need direct repository write access. See CONTRIBUTING.md.

ContextForge 0.4.2

and later are licensed under the Apache License 2.0. Earlier tagged releases remain available under the license included in those release snapshots. See NOTICE for the project attribution notice.

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