Capture the engineering decisions that matter. Replay them across every AI coding session.
Stop re-explaining. Stop losing key decisions. Stop wasting tokens. Stop architecture drift.
Keep every AI coding assistant and project aligned — and increase AI ROI.
Supported agents
- /claude code
- /cursor
- /codex
- /gemini cli
Your AI doesn't forget code.
It forgets why your team made certain decisions.
Architecture drift
The AI proposes solutions that violate architectural decisions your team made months ago - quietly, in code that compiles.
Tribal knowledge
Critical engineering knowledge lives inside senior engineers' heads instead of being available in every AI session.
Cross-agent inconsistency
Claude Code, Cursor, Codex, and Gemini CLI all produce different implementations because each one starts every session with different assumptions.
AI re-explanation tax
Every new coding session begins with re-explaining the same conventions, constraints, and architecture you've already approved.
Capture, propose, approve. Right inside your terminal.
These mockups show the intended flow. The actual UI may differ. The idea is decisions captured, reviewed, and replayed where your AI coding assistant already lives.
State a rule. Contexer stores it.
Directives you state outright become global conventions, loaded into every future session.
AI surfaces a decision mid-work.
Architecture and constraint decisions are parked for review, never replayed until you approve.
One keystroke. Versioned forever.
Approve, edit, or ignore. Approved decisions are immutable and replayed across every agent.
Same model. Same repo. Same question.
We ran Claude Sonnet 5 and Opus 4.8 across six memory conditions, scored by code — not a judge model. Here's one question, two runs.
540 sessions · 2 models · 6 conditions · deterministic scoring · independent validator · adversarial review · raw JSONL published
Engineering decisions. Not chat history.
"We standardized on PostgreSQL."
"Never expose S3 buckets publicly."
"Terraform modules live under infrastructure/modules."
"Every API emits OpenTelemetry traces."
These are engineering decisions - not chat history, not transcripts, not session logs.
AI agent memory remembers conversations. Contexer remembers the engineering decisions you approved.
CLAUDE.md, AGENTS.md, .cursorrules, and per-assistant memories capture whatever one person remembers to write down, and get overwritten with no review. Contexer captures typed engineering decisions, holds the risky ones for your approval, and versions them so the latest approved revision is what every agent sees.
Start free. Upgrade when your team grows.
Free
The same core product, available two ways. Use the local CLI and JSON store with no account, or sign in for managed cloud sync and the web dashboard.
MIT licensed · No account required for local OSS
Local JSON store. Fully offline. No web app or cloud. No account required.
Encrypted sync, web dashboard, and cross-machine replay.
- ✓Capture architecture, constraint, convention, and pattern decisions
- ✓AI-proposed decisions held for your review
- ✓Approve, edit, skip, or dismiss before replay
- ✓Injected into every Claude Code, Cursor, Codex, and Gemini CLI session
- ✓Web dashboard to review history and manage decisions (Cloud)
- ✓One-click upgrade to Teams
Teams
One repository per team. Invite members and share approved engineering decisions across everyone's AI coding sessions.
30-day free trial · No credit card required
- ✓Everything in Free Cloud
- ✓Unlimited team members with OAuth sign-in
- ✓One shared repository per team
- ✓Shared decision repository via team MCP endpoint
- ✓Role-based approval workflow (lead / member)
- ✓Confidence scores with supporting evidence - leads only
- ✓AI-generated canonical suggestions and updates
Organization
For orgs running multiple teams. Cross-team sharing, enforcement, CI/CD drift detection, SSO, and audit trail.
SSO · Audit trail · Pipeline drift detection
- ✓Everything in Teams
- ✓Cross-team decision sharing across the org
- ✓Enforcement policies (require approval, block on drift)
- ✓CI/CD pipeline hook - detects and rates architecture drift on every PR
- ✓SSO login (SAML, OIDC)
- ✓Full audit trail and access controls
- ✓Dedicated support and onboarding
Two commands. Under two minutes.
Requires Python 3.12+ and uv. Auto-detects Claude Code (~/.claude), Cursor (~/.cursor), Codex (~/.codex), and Gemini CLI (~/.gemini) and wires them in.
# Step 1. install $ uv tool install contexer # Step 2. wire into your AI assistant $ contexer install -> detected ~/.claude (Claude Code) -> detected ~/.cursor (Cursor) -> detected ~/.codex (Codex) -> detected ~/.gemini (Gemini CLI) -> wired all four. restart your AI assistant.
Restart your AI assistant and open any git repo. Contexer runs from there.
~26 tokens per rule. Paid once per session.
Only constraints and conventions are replayed every session. Architecture and pattern decisions cost nothing until the work actually needs them. Store lookups are sub-millisecond and run before the response is generated.
Deduplication is deterministic - >70% token overlap is dropped. No LLM call. No tokens.
## Project rules - apply to ALL tasks in this repo: - [convention] Use uv, not pip, for all dependency management - [constraint] Never commit untested code - CI blocks merges below coverage 2 architecture decision(s) stored. Call get_context before reading files for questions about architecture or rationale.
Get in touch
Questions, feedback, or partnership ideas - pick the channel that suits you best. We typically respond within one business day.