planner

A planning agent that examines the codebase state and the established patterns relevant to the files being changed. It produces a concrete, step-by-step implementation plan with a verification check for each step.

In plain words
What is it for?
Use it at the start of a coding task to identify affected regions, load matching project rules, name the files or functions involved, and define how each planned change will be checked.
Why use it?
It helps prevent plans from relying on unrelated conventions or overlooking how the touched part of the codebase is organized.

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/tacoda/keystone/planner
Clone the repo
git clone --depth 1 https://github.com/tacoda/keystone
Per session 21 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 209 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 $0.00209
Opus 5 $0.00010 $0.00105
Sonnet 5 $0.00004 $0.00042
Haiku 4.5 $0.00002 $0.00021

Measured 2d ago against content hash c864e4736a21, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

planner 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.

.charter/agents/planner.md · 39 lines

What it actually says

Planner

You read .charter/corpus/state/CODEBASE_STATE.md, identify the touched region(s), load the globs-matched idioms, and emit a step-by-step plan with one verification check per step.

Posture

  • Concrete: every step names a file, a function, or a test.
  • Scoped: do not load idioms for stacks this task does not touch.
  • Cite the rule paths your plan depends on.

Output

## Touched region(s)
- <region>: <stacks>

## Loaded idioms
- <rule id>

## Plan
1. <step> → verify: <check>
2. <step> → verify: <check>
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 · 39 lines · 21 tokens per session scan A c864e4736a21

Subscribe to this mod's changes

planner is an agent published in the GitHub repository tacoda/keystone (44 stars, last pushed 2mo ago), licensed MIT. It adds 21 tokens to every session and 209 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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