context-start

context-start is a skill for Claude Code, Codex from conorbronsdon/agent-context-os. It costs 42 tokens per session (1,050 once invoked), scanned A, original, MIT.

A workspace-session guide that loads the current project state, recent decisions, blockers, priorities, and continuity information. It requires a specific repository root containing AGENTS.md and scripts/contextos.sh.

In plain words
What is it for?
Use it when explicitly beginning or resuming a workspace session, before reading project files or running lifecycle commands.
Why use it?
It helps the agent resume work with the right context while preventing it from using the wrong directory.

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/conorbronsdon/agent-context-os/context-start
Any agent
npx skills add conorbronsdon/agent-context-os --skill context-start
Clone the repo
git clone --depth 1 https://github.com/conorbronsdon/agent-context-os

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for context-start

README.md
[![agentmods](https://agentmods.dev/badge/skills/conorbronsdon/agent-context-os/context-start.svg)](https://agentmods.dev/skills/conorbronsdon/agent-context-os/context-start)
Your own site
<a href="https://agentmods.dev/skills/conorbronsdon/agent-context-os/context-start"><img src="https://agentmods.dev/badge/skills/conorbronsdon/agent-context-os/context-start.svg" alt="Measured on agentmods" height="20"></a>
Per session 42 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,050 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 $0.00042 $0.01050
Opus 5 $0.00021 $0.00525
Sonnet 5 $0.00008 $0.00210
Haiku 4.5 $0.00004 $0.00105

Measured 2d ago against content hash e2897e79f7e4, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

context-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 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/skills/context-start/SKILL.md · 92 lines

How it starts

The opening of the file, as written. The whole thing — 92 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Start a workspace session

Execution roots (required)

Use the exact roots supplied by the host attachment: KernelRoot is the trusted Context OS product containing scripts/contextos.sh; ContextRoot owns tracked identity and lifecycle state; and WorkingRoot is the ordinary application. For an external attachment, require all three exact absolute paths and run:

bash <KernelRoot>/scripts/contextos.sh --context-root <ContextRoot> --working-root <WorkingRoot> <command>

Do not search upward or infer a root from cwd or the skill installation. The kernel must validate the ignored local binding before strict lifecycle work. A missing, moved, stale, linked, nested, or mismatched binding stops the workflow; use the explicit project rebind proposal after a legitimate move. ContextRoot owns all lifecycle writes. WorkingRoot is read-only evidence. The colocated bash scripts/contextos.sh <command> compatibility form remains valid.

Throughout this procedure, resolve routing, state, session, task, and local Context OS paths beneath ContextRoot. In split mode, invoke every lifecycle command through the absolute KernelRoot wrapper with both exact role options. In colocated mode, run the relative compatibility commands from the colocated root.

Resume from durable repository state instead of reconstructing context from chat history.

Procedure

  1. Run exactly one start form:

    split:     bash <KernelRoot>/scripts/contextos.sh --context-root <ContextRoot> --working-root <WorkingRoot> start
    colocated: bash scripts/contextos.sh start
    

    Treat its JSON as the deterministic inventory of configured paths, freshness, latest session, and role-qualified Git evidence. In colocated mode, the compatibility git_head describes the documented GitEvidenceScope, which may enclose ContextRoot. If the kernel is unavailable, stop and recommend the matching doctor form:

    split:     bash <KernelRoot>/scripts/contextos.sh --context-root <ContextRoot> --working-root <WorkingRoot> doctor
    colocated: bash scripts/contextos.sh doctor
    

Read the full file on GitHub · 92 lines

Files

What ships with it

1 file 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. 2d ago Changed · +34 lines e2897e79f7e4
  2. 4d ago First seen · 58 lines · 42 tokens per session scan A 364006b89f2d

Subscribe to this mod's changes

context-start is a skill published in the GitHub repository conorbronsdon/agent-context-os (21 stars, last pushed today), licensed MIT. It adds 42 tokens to every session and 1,050 once invoked, about $0.0002 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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