session-mode

session-mode is a skill for Claude Code, Codex from Arch1eSUN/Arcgentic. It costs 36 tokens per session (473 once invoked), scanned A, original, MIT.

A workflow for deciding whether a project uses one continuous session or several separate sessions, then producing prompts for the roles involved. It stores the decision in the project's state file.

In plain words
What is it for?
Use it to recommend or set a session mode, generate developer, auditor, or closeout prompts, and create a Codex-native host plan.
Why use it?
It prevents the same session-mode question from being asked repeatedly and keeps role handoffs consistent across development rounds.

Skill for Claude CodeCodex

Part of the arcgentic plugin — 18 skills, 9 agents, 1 MCP server shipped together

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/arch1esun/arcgentic/session-mode
Any agent
npx skills add Arch1eSUN/Arcgentic --skill session-mode
Clone the repo
git clone --depth 1 https://github.com/Arch1eSUN/Arcgentic

Made for: Claude Code, Codex.

Or install arcgentic, the plugin that ships this one along with the rest of its 18 skills, 9 agents, 1 MCP server.

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 session-mode

README.md
[![agentmods](https://agentmods.dev/badge/skills/arch1esun/arcgentic/session-mode.svg)](https://agentmods.dev/skills/arch1esun/arcgentic/session-mode)
Your own site
<a href="https://agentmods.dev/skills/arch1esun/arcgentic/session-mode"><img src="https://agentmods.dev/badge/skills/arch1esun/arcgentic/session-mode.svg" alt="Measured on agentmods" height="20"></a>
Per session 36 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 473 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 5.1 $0.00036 $0.00473
Opus 5 $0.00018 $0.00236
Sonnet 5 $0.00007 $0.00095
Haiku 4.5 $0.00004 $0.00047

Measured 6d ago against content hash aa3f13675176, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-05, from the pricing page.

Security

Grade A, and why

session-mode 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 6d 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.

skills/session-mode/SKILL.md · 60 lines

What it actually says

session-mode

Resolves project-level single-session vs multi-session execution and prints role-specific identity prompts. Once project.session_mode is present in .agentic-rounds/state.yaml, do not ask again per round.

Workflow

  1. Read .agentic-rounds/state.yaml and the round handoff.

  2. If project.session_mode.mode is already set, treat it as fact and skip the recommendation/choice step.

  3. If no project-level mode exists, generate a recommendation:

    arcgentic session-mode recommend \
      --round <round-id> \
      --handoff <handoff-path>
    
  4. Print recommendation, confidence, reasons, suggested role identities, and override instructions before asking the user to choose.

  5. Print only the identity handoff prompt needed for the next role:

    arcgentic session-mode prompt \
      --round <round-id> \
      --handoff <handoff-path> \
      --mode multi-session \
      --role developer
    

    V1 valid roles: developer, auditor, closeout.

  6. For V2 Codex-native orchestration, generate the fixed-role host plan instead of per-round role prompts:

    arcgentic v2-session-plan \
      --state .agentic-rounds/state.yaml \
      --host codex
    

    V2 session roles are fixed to Orchestrator, Planner, Developer, and Auditor. close-round is an orchestrator-owned command, not a session role.

Boundaries

  • Do not enter developer work before the mode gate is resolved.
  • Do not re-ask the user when project-level mode is already stored.
  • Do not claim single-session auto-audit when dispatch transport is unavailable.
  • In V1, developer, auditor, and closeout identity prompts must remain separate.
  • In V2, keep exactly four fixed role sessions and never create round-numbered role threads.
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. 6d ago First seen · 60 lines · 36 tokens per session scan A aa3f13675176

Subscribe to this mod's changes

session-mode is a skill published in the GitHub repository Arch1eSUN/Arcgentic (292 stars, last pushed 24d ago), licensed MIT. It adds 36 tokens to every session and 473 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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