fic-implement-plan

A command for carrying out an approved technical implementation plan stored in a project folder. It works through the plan in phases and tracks completed work.

In plain words
What is it for?
Use it to implement features, read the files and research named in a plan, run its verification commands, and record progress in the plan.
Why use it?
It prevents planned work from being skipped or implemented without checking the stated requirements and verification steps.

Command for Codex

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 commands/saski/arnesto/fic-implement-plan
Clone the repo
git clone --depth 1 https://github.com/saski/arnesto

Made for: Codex.

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 730 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 $0.00730
Opus 5 $0.00000 $0.00365
Sonnet 5 $0.00000 $0.00146
Haiku 4.5 $0.00000 $0.00073

Measured 2d ago against content hash 136002cc7536, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

fic-implement-plan 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/commands/fic-implement-plan.md · 126 lines

How it starts

The opening of the file, as written. The whole thing — 126 lines — stays where its author put it; the contents beside it link to each section on GitHub.

FIC Implement Plan - Execute Plans Phase by Phase

Act as a Senior XP Developer implementing an approved technical plan from thoughts/shared/plans/.

Task

Plan Path: $ARGUMENTS

If no path provided, ask: "Which plan should I implement? (e.g., thoughts/shared/plans/2025-01-08-feature.md)"

Implementation Process

Step 1: Read and Understand
  1. Read the plan completely

    • Check for existing checkmarks (- [x])
    • Understand all phases and success criteria
  2. Read referenced files

    • Original ticket if mentioned
    • Research documents
    • All files mentioned in the plan
  3. Create todo list to track progress

Step 2: Implement Phase by Phase

For each phase:

  1. Implement the changes

    • Follow the plan's specifications
    • Adapt to what you find (plans are guides, not scripts)
    • If something doesn't match, STOP and communicate:
      Issue in Phase [N]:
      Expected: [what plan says]
      Found: [actual situation]
      Why this matters: [explanation]
      
      How should I proceed?
      
  2. Run automated verification

    • Execute all success criteria commands
    • Fix any issues before proceeding
  3. Update progress

    • Check off completed items in the plan
    • Update todo list
  4. Pause for manual verification (only if plan has manual criteria)

    • If no manual verification in plan → Continue to next phase
    • If manual verification exists:
      Phase [N] Complete - Ready for Manual Verification
      
      Automated verification passed:
      - [List checks that passed]
      
      Please perform manual verification:
      - [List manual items from plan]
      
      Let me know when complete so I can proceed.
      
Step 3: Handle Mismatches

When things don't match the plan:

  • Think about WHY
  • The plan captures intent, but reality can differ
  • Communicate clearly before deviating
  • Document deviations in the plan
Step 4: Resume Partial Work

If plan has existing checkmarks:

  • Trust that completed work is done
  • Pick up from first unchecked item
  • Verify previous work only if something seems off

Read the full file on GitHub · 126 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 · 126 lines · 0 tokens per session scan A 136002cc7536

Subscribe to this mod's changes

fic-implement-plan is a command published in the GitHub repository saski/arnesto (5 stars, last pushed 6d ago), licensed Unlicense. It costs nothing until one of its globs matches a file; then it loads 730 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.