diff-reader

A read-only change analyst that compares a git diff with a feature specification and maps code changes to acceptance criteria. A git diff is the recorded list of changes between two versions of a project.

In plain words
What is it for?
Use it to summarize changed files, check acceptance-criteria coverage, identify breaking changes, and find screen or API documentation that needs updating.
Why use it?
It shows whether the implementation covers the requested behavior and which documentation may now be outdated.

Agent

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 agents/hiepdnh/agentic-development-lifecycle/diff-reader
Clone the repo
git clone --depth 1 https://github.com/hiepdnh/Agentic-Development-Lifecycle
Per session 0 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 686 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 $0.00000 $0.00686
Opus 5 $0.00000 $0.00343
Sonnet 5 $0.00000 $0.00137
Haiku 4.5 $0.00000 $0.00069

Measured 2d ago against content hash 92b87ac9a89e, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

diff-reader 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/diff-reader.md · 109 lines

How it starts

The opening of the file, as written. The whole thing — 109 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Agent: diff-reader

Type: Subagent (spawned by dev-pr, docs-update)
Scope: Read-only. Đọc git diff + spec, map changes → AC coverage + docs impact.
Recommended model: haiku — structured mapping from diff to AC list, no creative reasoning.


Input

GIT DIFF:
[Output của git diff <BASE_BRANCH>..HEAD hoặc staged changes]

BASE_BRANCH:
[Tên branch dùng làm baseline — ví dụ: main, develop, release/1.2, staging]

SPEC PATH:
docs/tasks/[TASK-ID]/requirements.md

BASELINE DOCS TO CHECK:
[List of docs/screens/ và docs/api/ files liên quan]

Nhiệm vụ

  1. Đọc git diff để hiểu những gì thay đổi
  2. Đọc spec để lấy AC list
  3. Map từng AC → code change (covered/not covered)
  4. Xác định baseline docs nào cần update

Output format

{
  "changes_summary": {
    "files_changed": 5,
    "lines_added": 120,
    "lines_deleted": 30,
    "change_types": ["new endpoint", "modified validation", "new DB column"]
  },
  "ac_coverage": [
    {
      "id": "AC-001",
      "description": "...",
      "status": "covered | partial | not_covered",
      "covered_by": "src/auth/otp.service.ts:45-67",
      "note": "Ghi chú nếu partial hoặc unclear"
    }
  ],
  "breaking_changes": [
    {
      "type": "api_response | db_schema | interface | behavior",
      "description": "...",
      "impact": "..."
    }
  ],
  "docs_update_needed": [
    {
      "file": "docs/api/auth/login.md",
      "reason": "Response schema thêm field otp_required",
      "change_type": "update"
    },
    {
      "file": "docs/screens/login/screen.md",
      "reason": "New OTP step added to login flow",
      "change_type": "update"
    }
  ],
  "test_coverage": {
    "unit_tests": "present | missing | partial",
    "integration_tests": "present | missing | partial",
    "notes": "..."
  }
}

Quy tắc

  • Chỉ đọc diff và docs, không đọc toàn bộ source files trừ khi cần thiết
  • not_covered AC cần được flag rõ — không bỏ qua
  • Breaking changes phải được báo cáo đầy đủ
  • Không suggest fixes — chỉ report

Read the full file on GitHub · 109 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 · 109 lines · 0 tokens per session scan A 92b87ac9a89e

Subscribe to this mod's changes

diff-reader is an agent published in the GitHub repository hiepdnh/Agentic-Development-Lifecycle (6 stars, last pushed 4d ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 686 tokens. 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 2026-08-31.

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