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.
npx agentmods add skills/capitalone/context-specs/implement-mainspecnpx skills add capitalone/context-specs --skill implement-mainspecgit clone --depth 1 https://github.com/capitalone/context-specsWhat 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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00066 | $0.01978 |
| Opus 5 | $0.00033 | $0.00989 |
| Sonnet 5 | $0.00013 | $0.00396 |
| Haiku 4.5 | $0.00007 | $0.00198 |
Grade A, and why
implement-mainspec 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.
How it starts
The opening of the file, as written. The whole thing — 160 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Implement Mainspec
Implements all slices from a mainspec in dependency order, sequentially. Agent-first: invoked headless by the harness dispatcher, runs end-to-end with no approval gates, exits.
Invocation Contract
Invoked by the dispatcher as: claude -p "/implement-mainspec <feature>", run from inside the feature worktree (the dispatcher cds into it).
Single argument: <feature> — kebab-case feature slug. The mainspec path is specs/<feature>/mainspec.md relative to cwd.
Inputs read from disk (paths relative to cwd):
specs/<feature>/mainspec.mdspecs/<feature>/slices/*.md- Current
feature/<feature>branch state.
Outputs to disk / remote:
- All implementation code committed and pushed on
feature/<feature>, one commit per slice.
No sentinel. The dispatcher's success signal for this step is ./prds/<feature>/run-prd-test.sh exits 0, verified externally. The final slice's Success Criteria encodes this into a slice so completing all slices implies the PRD test passes. We do not write a sentinel file — the dispatcher records the green result in specs/<feature>/.prd-passed once the runner first exits 0; this skill neither writes nor reads that file.
Idempotency:
- On every invocation, inspect
feature/<feature>git history. Determine which slices are already committed (look for commits likeImplement slice <n>: <name>). - The orchestrator reads the mainspec's Slice Dependency Map inline to plan its execution order.
- Work only on remaining slices.
- If all slices appear committed, exit cleanly. The dispatcher will re-verify the PRD test externally.
No approval gates anywhere. No AskUserQuestion for plan approval, default-branch warning, or any other decision. Every decision is deterministic or deferred to the next dispatcher tick.
Workflow Overview
Phase 1: Parse & Resume — Read mainspec Slice Dependency Map, determine execution order, inspect feature/<feature> for already-committed slices
Phase 2: Implement — Delegate each remaining slice to slice-implementer subagent (foreground). Orchestrator handles git directly on feature/<feature>.
Phase 3: Log — Log final status of this invocation to stdout for observability
What ships with it
2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 2d ago First seen · 160 lines · 66 tokens per session scan A ec5aa58868ab
implement-mainspec is a skill published in the GitHub repository capitalone/context-specs (41 stars, last pushed 8d ago), licensed Apache-2.0. It adds 66 tokens to every session and 1,978 once invoked, about $0.0003 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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