apply-feature-knowledge

A guide for using precomputed feature knowledge as supporting context when working on a code feature.

In plain words
What is it for?
Use it to review feature notes, apply documented patterns and gotchas, and verify them against the files you are changing.
Why use it?
It gives useful patterns, warnings, and integration points without treating old documentation as more authoritative than the current code.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/dean0x/devflow/apply-feature-knowledge
Any agent
npx skills add dean0x/devflow --skill apply-feature-knowledge
Clone the repo
git clone --depth 1 https://github.com/dean0x/devflow

Made for: Claude Code, Codex.

Per session 20 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 548 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00020 $0.00548
Opus 5 $0.00010 $0.00274
Sonnet 5 $0.00004 $0.00110
Haiku 4.5 $0.00002 $0.00055

Measured 2d ago against content hash 584e83392c19, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

apply-feature-knowledge scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

src/assets/skills/apply-feature-knowledge/SKILL.md · 70 lines

How it starts

The opening of the file, as written. The whole thing — 70 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Apply Feature Knowledge

Iron Law

Pre-computed context, not a cage. Verify against current code — always.

A feature knowledge captures patterns AS THEY WERE when last written. Code evolves. Use the feature knowledge as a starting point, not gospel truth. When something feels off, Read the actual files. Code is authoritative; feature knowledge is supplementary.


3-Step Algorithm

Step 1: Read the Feature Knowledge

When FEATURE_KNOWLEDGE is provided and is not (none):

  1. Read each feature knowledge section (separated by --- Feature knowledge: {slug} --- headers)
  2. Absorb: architecture, data flow, key patterns, anti-patterns, gotchas
  3. Note integration points that relate to your current task

Step 2: Apply to Current Task

  1. Patterns as defaults: Follow documented patterns unless you have a specific reason not to
  2. Anti-patterns as warnings: Check your work against documented anti-patterns
  3. Gotchas as checklists: Verify each gotcha doesn't apply to your changes
  4. Integration points: Ensure your changes respect documented boundaries
  5. Key files: Use as starting points for exploration

Step 3: Verify Against Current Code

The feature knowledge may not reflect recent changes:

  • If the feature knowledge doesn't address your specific area, explore further
  • When an assertion seems outdated: Read the relevant source files to confirm — code wins
  • When you find a contradiction between the KB and actual code, trust the code
  • Note discrepancies in your output when they matter for the task

Skip Guard

When FEATURE_KNOWLEDGE is (none), empty, or not provided — skip this skill entirely. Do not mention feature knowledge or its absence in your output.

Freshness Model

Feature knowledge uses write-through + verify-on-read for freshness:

  • KBs are written at the point a documented area changes (not on a background schedule)
  • Readers verify key assertions against current code rather than relying on staleness markers
  • When in doubt, Read the file — that resolves any uncertainty immediately

Read the full file on GitHub · 70 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 70 lines · 20 tokens per session scan A 584e83392c19

Subscribe to this mod's changes

apply-feature-knowledge is a skill published in the GitHub repository dean0x/devflow (19 stars, last pushed 2d ago), licensed MIT. It adds 20 tokens to every session and 548 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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