lifan-builds Context Harness
4 files, lean rules, zero ceremony. Context window = volatile RAM. Filesystem = persistent storage. Write anything important to disk before it scrolls away.
Companion Skills
Use the smallest skill that matches the agent's intent:
| Intent | Skill |
|---|---|
| New repo or missing context files | context-init |
| Fresh agent session, true resume, or "catch me up" | context-catch-up |
| Convert conversation into a long-running goal or loop-mode prompt | set-goal |
| Context updates, lesson capture, plan stress-tests, plan/NOW updates, closeout, reflection, Dream/Compact consolidation | context-maintain |
| Explicitly requested context-harness update or project-context migration | context-upgrade |
context-upgrade is explicit-only and should not be implicitly invoked.
Behavioral Principles
- Think before coding — State assumptions explicitly. If ambiguous, ask. Don't guess scope, format, or intent.
- Simplicity first — If 200 lines could be 50, rewrite. No speculative abstractions, premature error handling, or unnecessary indirection.
- Surgical changes — Every changed line traces directly to the user's request. Don't refactor adjacent code, change formatting, or "improve" unrelated things.
- Goal-driven loops — Transform vague goals into testable checkpoints. Write failing test, implement, verify, check regressions. Loop until done.
Core Rules
- Tool-native first — Prefer CLI, MCP tools, or skills over browser automation when they can do the job. Reserve browser automation for browser-specific workflows, visual verification, and web UIs with no better interface.
Determine Mode
| Condition | Mode |
|---|---|
No CONTEXT.md at project root |
Use context-init |
CONTEXT.md exists and the agent is at a fresh-session or true-resume boundary |
Use context-catch-up |
| The user wants a plan challenged against docs, terms, and code | Use context-maintain Plan Stress-Test |
| The user wants a long-running goal for goal mode, loop mode, or a fresh agent | Use set-goal |
| The agent needs to update context, preserve a lesson, correction, plan, or session state | Use context-maintain |
| The user explicitly asks to upgrade context-harness itself, migrate schema versions, or repeat a local fleet migration | Use context-upgrade |
| Legacy, partial, old, or custom context-harness files exist | Use context-upgrade |
Init Mode
Run node scripts/context-gen.js to auto-detect project info, structure,
stack-specific Suggested Operating Constraints, Suggested Workflow, and Memory Prompts.
Fallback: scan package.json/pyproject.toml/Cargo.toml/go.mod manually.
Present ## Suggested Operating Constraints and ## Suggested Workflow as starting points; the user keeps only project-specific constraints a future agent would not infer from code or docs, and confirms verification commands.
Use PLAN.md Done Criteria for task outcomes and CONTEXT.md Workflow Verification for commands.
Step 3: Generate CONTEXT.md + NOW.md + AGENTS.md
Write the context files to the project root using the templates below, then run
node <context-harness-skill-dir>/scripts/install-project.js. For Codex,
AGENTS.md is the automatic activation layer. Keep it small: after writing or
changing CONTEXT.md, run node scripts/context-index.js update so
AGENTS.md contains only the contract plus a generated index.
Step 4: Optional PLAN.md
Ask: "Do you have a multi-step task to plan?" If yes, create PLAN.md.
Templates
CONTEXT.md
# Context
<!-- context-harness:schema v3 -->
## Project
[Auto-generated: name, tech stack, description.]
## Structure
[Auto-generated: directory tree, 5-10 lines.]
## Operating Constraints
<!-- Project-specific constraints future agents would not reliably infer. Keep short. -->
- [Constraint that changes agent decisions.]
## Workflow
- Setup: [install command]
- Run: [dev command]
- Test: [test command]
- Lint: [lint command]
### Verification
- [Required command or manual check before completing relevant work.]
## Language
<!-- Durable terms and agent discoveries. Keep concise. -->
- **[Canonical term]**: [Definition]. Avoid: [ambiguous synonym].
## Relationships
- [Invariant or domain relationship worth preserving.]
## Flagged Ambiguities
- [Resolved naming or meaning conflict.]
## Learned Patterns
<!-- Lessons after corrections, loops, or failed attempts. -->
[Max 10 entries. Use `- When [context], [do/avoid] because [evidence].`]
Optional: add CONTEXT-MAP.md only when one root context becomes ambiguous.
NOW.md
# Now
## Current Focus
[One sentence: what you are actively working on.]
## Active Blockers
- [Any blocking issues, or "None."]
## Immediate Next Step
[The very next action to take when resuming.]
## Session State
- Last modified: [ISO timestamp]
- Files touched: [comma-separated list]
NOW.md rules: Keep it concise. Rewrite entirely on task switch (never append). First file read on recovery, last file written before session end.
AGENTS.md
# Agent Instructions
<!-- context-harness:schema v3 -->
## Context Contract
- At a fresh session or true resume, read the small `NOW.md` packet first.
- If the user supplied an objective, question, or context, hydrate with it and
read only selected durable context. Otherwise hydrate from `NOW.md` focus and
next step.
- Reconcile user context with repository state, prefer the user's current
objective when scope changed, and surface material conflicts.
- Reuse loaded context on ordinary follow-ups; catch up again only after a real
context boundary, materially different objective, or external context change.
- Use `node scripts/context-index.js hydrate "<task>"` before opening `PLAN.md`,
chunks, or bulky/task-specific context.
- Read concise `CONTEXT.md` directly while it fits the startup budget; otherwise
use selected cards/sections. Respect `## Operating Constraints` before edits.
- Do not let non-blocking harness maintenance replace the requested work.
- Route task-local findings/decisions to `PLAN.md`; durable terms, constraints,
corrections, and lessons to `CONTEXT.md`.
- After any update to `CONTEXT.md`, `PLAN.md`, or `NOW.md`, run
`node scripts/context-index.js update`.
- Before ending, rewrite `NOW.md` from the observed final state after the last
commit, push, deployment, rollback, task switch, or blocker discovery.
## Context Index
<!-- context-harness:index:start -->
Generated from context sources; read small `CONTEXT.md` directly and use hydrate before bulky detail.
<!-- context-harness:index:end -->
PLAN.md (on-demand)
# [Task Title]
## Goal
[What the user can do after this is complete. 1-2 sentences.]
## Done Criteria
- [Observable or testable completion criterion.]
## Progress
- [ ] Step 1
- [ ] Step 2
## Verification
- [Command/check to run and expected result.]
## Findings
[Task-local research, discoveries, errors, and low-confidence lessons.]
## Decisions
[Non-trivial decisions with rationale.]
## Archive
[Summarized completed phases. Used when active state becomes cluttered.]
.context-harness/DREAM.md (lazy)
Created only after an automatic Dream/Compact pass changes context files. This is a non-operational audit log for debugging context drift or human review; agents must not read it during normal catch-up or task work.
Progressive Context Library (generated)
node scripts/context-index.js update also maintains .context-harness/index.json,
.context-harness/cards/, and .context-harness/chunks/. NOW.md plus concise
CONTEXT.md are the always-read layer. Use node scripts/context-index.js hydrate "<task>" to select cards before opening PLAN.md, chunks, or bulky
sections; open raw chunks only when a card says the detail is needed.
Context Rules
| Rule | Detail |
|---|---|
| Always-read layer | Read NOW.md first and concise CONTEXT.md with it. Use hydrate before PLAN.md, chunks, or bulky/task-specific context. |
| NOW.md contract | Update before session end. Rewrite on task switch. Keep concise. First read, last write. |
| Capture human input | If the user teaches a term, invariant, workflow, or constraint, write it to CONTEXT.md before it scrolls away. |
| Reflection routing | Task-local → PLAN.md Findings; durable process lesson → CONTEXT.md Learned Patterns; term → Language; invariant → Relationships; decision → PLAN.md Decisions unless the project already uses ADRs; skill correction → that skill's SKILL.md. |
| Learn after struggle | >2 attempts on a problem → distill lesson to CONTEXT.md § Learned Patterns |
| Prune patterns | Max 10 Learned Patterns. When full, remove the oldest entry. |
| Dream check | Every context-maintain run asks whether future catch-up would benefit from consolidation. If yes, compact bulky durable detail in source context or project docs, regenerate cards/chunks, verify with hydrate, and log to .context-harness/DREAM.md. |
| PLAN.md pruning | When active state is cluttered, summarize completed Progress into Archive and remove originals. |
| No raw external content | Don't paste raw URLs, API responses, or web content into CONTEXT.md. Summarize findings in PLAN.md § Findings. |
Companion Scripts
All scripts are Node.js and share helpers in scripts/lib.js. Adding a script?
Import from lib.js; don't duplicate hook I/O, root walk, stack detection, or
markdown helpers.
| Script | Purpose | When to use |
|---|---|---|
scripts/lib.js |
Shared helpers | Imported by every other script |
scripts/install-project.js |
Copy current v3 runtime scripts into a target repo | Init mode |
scripts/codex-context-hook.js |
Codex lifecycle hook dispatcher for catch-up, init, and maintain nudges | Codex hooks |
scripts/context-gen.js |
Auto-detect project metadata + emit stack-aware rule defaults | Init mode, Update mode |
scripts/context-index.js |
Update/list/query/print/stats/hydrate/check context sections and cards | After CONTEXT.md changes |
scripts/eval-agent-problem-solving.js |
Prepare/score fresh-agent problem-solving evals comparing no-harness vs progressive-harness modes | Real-world context-harness evaluation |
scripts/guard.js |
Block --no-verify, detect secrets, protect linter configs | Runs automatically via PreToolUse hook |
scripts/format-on-edit.js |
Auto-format files after edits | Runs automatically via PostToolUse hook |
scripts/session-end.js |
Stamp NOW.md; best-effort prune of completed PLAN.md items when very long | Runs automatically via Stop hook |
scripts/task.js |
Task switcher — rewrites NOW.md; logs to PLAN.md Progress | Run on task start / done |
node scripts/task.js start "Implement auth middleware"
node scripts/task.js done
start rewrites NOW.md and logs prior focus to PLAN.md. done marks NOW.md
idle and logs completion to PLAN.md Progress.
Non-Goals
No skill composition, subagent dispatch, mandatory worktrees, per-developer journals, or heavyweight knowledge base. Keep memory durable but small.