write-tech-spec

A repository-aware guide for writing a technical specification: a document that explains how a substantial or unclear software change should fit the existing code.

In plain words
What is it for?
It helps inspect the repository, record relevant code references and risks, and produce an implementation plan for review.
Why use it?
It reduces guesswork when work spans multiple parts of a codebase or involves architectural choices, migrations, or rollout plans.

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/terry-mao/aicodingflow/write-tech-spec
Any agent
npx skills add Terry-Mao/AICodingFlow --skill write-tech-spec
Clone the repo
git clone --depth 1 https://github.com/Terry-Mao/AICodingFlow

Made for: Claude Code, Codex.

Per session 21 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 650 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 $0.00021 $0.00650
Opus 5 $0.00010 $0.00325
Sonnet 5 $0.00004 $0.00130
Haiku 4.5 $0.00002 $0.00065

Measured 2d ago against content hash fd26cfa5123f, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

write-tech-spec 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.

.agents/skills/write-tech-spec/SKILL.md · 67 lines

How it starts

The opening of the file, as written. The whole thing — 67 lines — stays where its author put it; the contents beside it link to each section on GitHub.

write-tech-spec

Translate approved product intent into an implementation plan that fits the existing codebase. This is a local shared skill; wrappers may provide exact inputs and output paths that take precedence.

Decide and research

Use it when work spans modules, has architectural tradeoffs, needs a migration or rollout plan, or benefits from review before implementation. Skip it for straightforward fixes, small refactors, and narrow UI changes with no technical ambiguity. Prefer a product spec first; an end-to-end prototype can be a better precedent when the implementation is still uncertain.

Before drafting, read the product spec when present and inspect the actual repository. Identify current behavior, relevant files/types/entry points, data or control flow, ownership boundaries, dependencies, risks, and validation constraints. Do not infer architecture that can be read from code.

When a code reference matters, pin it to the inspected commit SHA and include a repo-relative path with line numbers. Add a GitHub blob/<sha>/...#Lx-Ly link when the repository has an accessible remote; otherwise keep the local reference. Reference the product spec for behavior rather than restating it.

Write the spec

Use the following core sections, keeping each only as detailed as the decision requires:

  1. Problem — the technical problem and its product relationship.
  2. Relevant code — files, symbols, entry points, and current ownership.
  3. Current state — how the system works and limitations that matter.
  4. Proposed changes — affected modules, types/APIs/state, data flow, ownership boundaries, sequencing, and tradeoffs.
  5. Testing and validation — map tests, manual checks, screenshots/videos, or other evidence to the product behavior and its numbered invariants.

Add these sections when they add signal:

  • End-to-end flow — when tracing the main path clarifies the change list.
  • Risks and mitigations — when there are real regression, migration, rollout, or compatibility hazards.
  • Follow-ups — when there is deferred technical debt or an open technical question.

Read the full file on GitHub · 67 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 · 67 lines · 21 tokens per session scan A fd26cfa5123f

Subscribe to this mod's changes

write-tech-spec is a skill published in the GitHub repository Terry-Mao/AICodingFlow (165 stars, last pushed 4d ago), licensed MIT. It adds 21 tokens to every session and 650 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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