epiq: Skill for Claude Code

.claude/skills/epiq-architecture/SKILL.md

epiq-architecture is a skill for Claude Code from ljtn/epiq. It costs 55 tokens per session (1,206 once invoked), scanned A, original, MIT.

Architecture rules for epiq’s event log, which records changes as ordered events. They define how events are ordered, merged, replayed, deleted, synchronized, and turned into current data.

In plain words
What is it for?
Use it before modifying event handling, synchronization, merging, replay, materialized data, or adding a new event type.
Why use it?
Following these rules prevents changes from breaking the event system’s ordering and replay behavior.

Skill for Claude Code

Written for Claude Code: installed under .claude/.

This is ljtn/epiq's own configuration. It tells Claude Code how to work on epiq itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything epiq configures →

Reuse

Borrowing it

Nothing to install: this file belongs to ljtn/epiq. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/ljtn/epiq/main/.claude/skills/epiq-architecture/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/ljtn/epiq

Made for: Claude Code.

Wrote this? Show the measurements

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agentmods badge for epiq-architecture

README.md
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agentmods 80×15 button for epiq-architecture

Your own site · 80×15
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Per session 55 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,206 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
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 $0.00055 $0.01206
Opus 5 $0.00028 $0.00603
Sonnet 5 $0.00011 $0.00241
Haiku 4.5 $0.00006 $0.00121

Measured 6d ago against content hash 56f7e4ebb034, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

epiq-architecture 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.

.claude/skills/epiq-architecture/SKILL.md · 60 lines

How it starts

The opening of the file, as written. The whole thing — 60 lines — stays where its author put it; the contents beside it link to each section on GitHub.

The event log is a CRDT

There is no server and no shared clock. Every actor appends to its own JSONL log on the state branch, git merges them, and each machine derives the same board from the same set. Everything below exists to keep that derivation a pure function of the event set.

The model

  • id = [ulid, refId]. refId is the causal parent: the tail of the causal order this actor last saw (getEdgeRef). Concurrent writers legitimately share a parent.
  • Order is derived, never stored. getSortedEvents rebuilds the forest from refId, sorts concurrent siblings by ULID, walks depth-first, and dedupes by id. File line order is not load-bearing.
  • The ULID is a hybrid logical clock, not a timestamp: getNextId(Math.max(Date.now(), decodeTime(edge) + 1)). The wall clock is only a lower bound; causality forces monotonicity.
  • Actor id comes from the file name; the display name does not. persist calls stripActor, so the payload carries neither. The id is parsed from the log's file name; the name is resolved from the contributor registry, which create.contributor / rename.contributor build. The name segment in the file name is a sanitized storage key, not a name of record.
  • Same event set ⇒ same order ⇒ same board. That is the whole contract.

Invariants

  • Derive order from refId plus the ULID tiebreak. Nothing else.
  • Ids are permanent. Tombstone instead: tombstoneNode marks the node and its descendants isDeleted; tombstoneContributor clears the display name but keeps the record so assignments referencing the id still resolve.
  • Replay is total. An event that lost a race or names state this replay never applied is a materializeSkip (ConvergenceFail) and is skipped. The same precondition on a live write is a genuine failure — there the precondition is the answer the caller asked for.
  • Unreadable stays ordered. The envelope (v, id) parses even when the payload cannot, so an event from a newer build keeps its place in the chain.
  • Append only. One id always means one byte sequence. This is what makes *.jsonl merge=union safe.
  • Time travel cuts causally. splitEventsAtTime marks a child unapplied when its parent is unapplied, whatever its own timestamp says.

Read the full file on GitHub · 60 lines

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 Changed · +9 lines 56f7e4ebb034
  2. 10d ago First seen · 51 lines · 55 tokens per session scan A 7776b12c0a6a

Subscribe to this mod's changes

epiq-architecture is a skill published in the GitHub repository ljtn/epiq (366 stars, last pushed yesterday), licensed MIT. It adds 55 tokens to every session and 1,206 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 2026-08-30.

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