append-only-sidechain-transcripts

append-only-sidechain-transcripts is a skill for Claude Code, Codex from ychampion/cskill-agents. It costs 32 tokens per session (350 once invoked), scanned A, original, MIT.

A storage method that keeps each subagent message as a permanent, ordered transcript entry. A subagent is a separate AI worker helping with part of a task.

In plain words
What is it for?
Use it to save subagent transcripts, track parent-child relationships, and replay a side task in order.
Why use it?
It preserves the exact sequence needed to resume or review work without rewriting earlier history or duplicating entries.

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/ychampion/cskill-agents/append-only-sidechain-transcripts
Any agent
npx skills add ychampion/cskill-agents --skill append-only-sidechain-transcripts
Clone the repo
git clone --depth 1 https://github.com/ychampion/cskill-agents

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 append-only-sidechain-transcripts

README.md
[![agentmods](https://agentmods.dev/badge/skills/ychampion/cskill-agents/append-only-sidechain-transcripts.svg)](https://agentmods.dev/skills/ychampion/cskill-agents/append-only-sidechain-transcripts)
Your own site
<a href="https://agentmods.dev/skills/ychampion/cskill-agents/append-only-sidechain-transcripts"><img src="https://agentmods.dev/badge/skills/ychampion/cskill-agents/append-only-sidechain-transcripts.svg" alt="Measured on agentmods" height="20"></a>
Per session 32 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 350 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 $0.00032 $0.00350
Opus 5 $0.00016 $0.00175
Sonnet 5 $0.00006 $0.00070
Haiku 4.5 $0.00003 $0.00035

Measured 5d ago against content hash 384dfbee0383, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

append-only-sidechain-transcripts 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 5d 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/claude-code/skills/append-only-sidechain-transcripts/SKILL.md · 28 lines

What it actually says

SKILL: Append-Only Sidechain Transcripts

Domain: session-storage Trigger: Subagent transcript persistence must stay append-only so forked history can be resumed and sidechain readers see messages in strict chronological order. Source Pattern: Distilled from reviewed subagent orchestration, isolation, and lifecycle implementations.

Core Method

Model each subagent transcript as an append-only event log with explicit ordering links or sequence checkpoints. Persist the seed messages once at startup, then append only durable milestones as the run progresses, ignoring ephemeral stream fragments that are not worth replaying later. Advance the transcript cursor only after a durable record is safely written so resumes, forks, and sidechain readers can reconstruct history in strict order without duplication.

Key Rules

  • Never rewrite, truncate, or backfill earlier transcript entries once they have been committed.
  • Filter out ephemeral deltas and other transient stream fragments so the stored transcript contains only meaningful replay points.
  • Advance the ordering cursor only after a durable write succeeds.
  • Partition transcript storage by agent or workflow so replay stays local and sidechains do not collide.

Example Application

When a workflow manager resumes a paused child agent, it can replay the append-only transcript to rebuild context exactly once and continue from the last durable checkpoint.

Anti-Patterns

  • Writing directly from raw streaming deltas or duplicating seed messages will corrupt the append-only history.
  • Advancing the cursor before persistence succeeds can create gaps, races, or duplicate replay on resume.
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. 5d ago First seen · 28 lines · 32 tokens per session scan A 384dfbee0383

Subscribe to this mod's changes

append-only-sidechain-transcripts is a skill published in the GitHub repository ychampion/cskill-agents (36 stars, last pushed 5mo ago), licensed MIT. It adds 32 tokens to every session and 350 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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