session:start

A skill for starting focused work sessions with the right project background. The session types are planning, building, reviewing, fixing bugs, and writing documentation.

In plain words
What is it for?
Use it at the beginning of project work to select a session type, load relevant guidance, and identify whether project setup is missing.
Why use it?
It loads only the initial context needed for the chosen task and checks whether the project has the required session structure.

Skill for Claude CodeCodex

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/gh33k/session-plugin/start
Any agent
npx skills add gh33k/session-plugin --skill start
Clone the repo
git clone --depth 1 https://github.com/gh33k/session-plugin

Made for: Claude Code, Codex.

Per session 54 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 606 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 $0.00054 $0.00606
Opus 5 $0.00027 $0.00303
Sonnet 5 $0.00011 $0.00121
Haiku 4.5 $0.00005 $0.00061

Measured yesterday against content hash 8dbabb407d92, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

session:start 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 yesterday.

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/start/SKILL.md · 97 lines

How it starts

The opening of the file, as written. The whole thing — 97 lines — stays where its author put it; the contents beside it link to each section on GitHub.

session:start

Start a session with type-appropriate context. Load orientation, not information.

Session Types

Type Purpose Context
plan Design work overview, constitution, state
build Implement state, conventions, feature files
review Code review conventions, git history
fix Debug state, recent sessions
document Update docs overview, constitution

Instructions

1. Determine Type

If type not provided or invalid, ask:

Session type? [plan/build/review/fix/document]

2. Verify Structure

ls -d .project 2>/dev/null

If .project/ does NOT exist:

No session structure found.

Run /session:init to:
- Analyze your codebase (detects stack, framework, conventions)
- Create .project/ with pre-filled templates
- Set up .context/ for session memory
- Initialize beads for task tracking

Then return here with /session:start {type}

Stop here - do not continue without structure.

3. Load Type-Specific Context

Read the appropriate reference file and follow its instructions:

4. Create Session File

ID format: {YYYY-MM-DD}-{type}-{3-random-chars}

Create .context/sessions/{id}.md:

# Session {date} ({type})

Goal: {user's goal}

Context loaded:
- {files loaded}

Progress:
- [ ] {goal as task}

5. Confirm and Begin

{TYPE} session started.
Focus: {from state.md if exists}
Session: .context/sessions/{id}.md

What are we working on?

Progressive Disclosure Principle

Load ORIENTATION, not INFORMATION:

  • Show file paths, not file contents (Claude reads when needed)
  • Show task IDs, not full task details (use bd show when needed)
  • Extract key sections from state.md, not the whole file

Read the full file on GitHub · 97 lines

Files

What ships with it

5 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.

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. yesterday First seen · 97 lines · 54 tokens per session scan A 8dbabb407d92

Subscribe to this mod's changes

session:start is a skill published in the GitHub repository gh33k/session-plugin (2 stars, last pushed 7mo ago), licensed MIT. It adds 54 tokens to every session and 606 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 2026-08-31.