sdd:implement

A Spec-Driven Development command that carries out the tasks in a written feature plan. It can run checkpoints and configured hooks, update progress records, create a feature branch when configured, commit changes, and open a pull request.

In plain words
What is it for?
Executing planned coding tasks, recording implementation events, running configured checks, committing the result, and opening a pull request.
Why use it?
It coordinates the implementation workflow and keeps task progress and history recorded as the work proceeds.

Skill for Claude CodeCodex

Part of the sdd plugin — 11 skills shipped together

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/alfredoperez/sdd/implement
Any agent
npx skills add alfredoperez/sdd --skill implement
Clone the repo
git clone --depth 1 https://github.com/alfredoperez/sdd

Made for: Claude Code, Codex.

Or install sdd, the plugin that ships this one along with the rest of its 11 skills.

Per session 24 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 6,085 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 $0.00024 $0.06085
Opus 5 $0.00012 $0.03043
Sonnet 5 $0.00005 $0.01217
Haiku 4.5 $0.00002 $0.00609

Measured 2d ago against content hash b32c881bc9e2, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

sdd:implement 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.

skills/implement/SKILL.md · 442 lines

How it starts

The opening of the file, as written. The whole thing — 442 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Shared Instructions

  • Event Journal — append context updates to a per-spec write-ahead log; a single drain script materializes them into .spec-context.json
  • Transition Logging — transition entry shape and millisecond at precision (the drainer materializes one transition per journal event)
  • Hook Execution — run user-configured hooks at supported pipeline points
  • Branch Creation — optional feature-branch creation driven by .sdd.json branchStage
  • Layered Context — Layer 2 → Layer 1 delta sync at CP3 (Step 7b)

Context writes: journal + drain

This skill does not read-merge-write .spec-context.json on every task. Per event-journal, each context update is a one-line append to specs/{NNN}-{slug}/.spec-context.events.jsonl (cheap; no read, no merge), and a single drain materializes the journal into .spec-context.json at the boundaries called out below.

  • On entry, read drainedSeq from .spec-context.json (default 0) and the last journal line's seq (default 0); set your run counter to the max. Each append increments it by 1. Each append carries at (ms precision via date -u +%Y-%m-%dT%H:%M:%S.%3NZ), the current step/substep, and the from (prior step+substep) — the drainer turns each event into exactly one transition.
  • To drain, run:
    python3 lib/scripts/drain-spec-context.py specs/{NNN}-{slug}/
    
    Drain at: Context Recovery (first), every ~3 solo tasks and before yielding the turn, each parallel-group end, before each checkpoint display (CP1/CP2/CP3), and before git add in Steps 8 and 8b. The drainer is idempotent.

Steps

1. Load

If $ARGUMENTS is provided, use specs/{$ARGUMENTS}/ as the target directory. Otherwise, find the most recently modified directory under specs/ that contains tasks.md.

Read the full file on GitHub · 442 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 · 442 lines · 24 tokens per session scan A b32c881bc9e2

Subscribe to this mod's changes

sdd:implement is a skill published in the GitHub repository alfredoperez/sdd (2 stars, last pushed 11d ago), licensed MIT. It adds 24 tokens to every session and 6,085 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 2026-08-31.

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