fork-gap-fill-reconstruction

fork-gap-fill-reconstruction is a skill for Claude Code, Codex from ychampion/cskill-agents. It costs 26 tokens per session (394 once invoked), scanned A, original, MIT.

A way to rebuild a resumed child agent's replacement state from its own saved records and any missing entries in the parent's live state.

In plain words
What is it for?
Restoring forked or resumed workflows while preserving previously chosen replacements and avoiding recalculation.
Why use it?
A resumed child may lack some replacement decisions from its earlier run, causing it to show different cached previews or repeat work.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Restoring forked or resumed workflows while preserving previously chosen replacements and avoiding recalculation.

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Install with agentmods
npx agentmods add skills/ychampion/cskill-agents/fork-gap-fill-reconstruction
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.

Any agent
npx skills add ychampion/cskill-agents --skill fork-gap-fill-reconstruction
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 fork-gap-fill-reconstruction

README.md
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Your own site
<a href="https://agentmods.dev/skills/ychampion/cskill-agents/fork-gap-fill-reconstruction"><img src="https://agentmods.dev/badge/skills/ychampion/cskill-agents/fork-gap-fill-reconstruction/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

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Your own site · 80×15
<a href="https://agentmods.dev/skills/ychampion/cskill-agents/fork-gap-fill-reconstruction"><img src="https://agentmods.dev/badge/skills/ychampion/cskill-agents/fork-gap-fill-reconstruction.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 26 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 394 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.
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 $0.00026 $0.00394
Opus 5 $0.00013 $0.00197
Sonnet 5 $0.00005 $0.00079
Haiku 4.5 $0.00003 $0.00039

Measured 6d ago against content hash 9ea0198a7bb4, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

fork-gap-fill-reconstruction 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.

agents/claude-code/skills/fork-gap-fill-reconstruction/SKILL.md · 28 lines

What it actually says

SKILL: Fork Gap-Fill Reconstruction

Domain: multi-agent
Trigger: Apply when a forked or resumed child workflow must inherit prior replacement decisions even though its local transcript lacks full replacement records. Source Pattern: Distilled from reviewed multi-agent coordination and child-runtime patterns.

Core Method

Rebuild child state from the records the child actually persisted, then fill any uncovered IDs from the parent's live replacement map. This handles the fork-resume case where inherited replacements were applied during the original run but never written as new child records. The result is a child state that replays the same cached previews the model originally saw instead of freezing those IDs as unreplaced gaps.

Key Rules

  • Reconstruct from local records first so the child transcript remains the primary source of truth for what it explicitly persisted.
  • Use parent replacements only as a gap-fill for IDs still present in the resumed messages and not already covered by child records.
  • Preserve the seenIds freeze semantics while layering in inherited replacements so resumed children do not recalculate different decisions.
  • Skip inherited mappings for IDs absent from the resumed message set; they are inert and should not pollute the child state.

Example Application

When a forked review agent resumes from sidechain transcript records, rebuild its replacement state from those records and then copy any missing preview strings from the parent’s live replacement map so the resumed child continues using the exact previews it saw before the interruption.

Anti-Patterns (What NOT to do)

  • Do not rely on child records alone for fork-resume cases; inherited replacements may never have been persisted by the child.
  • Do not blindly copy the entire parent replacement map into the child; only IDs present in the resumed messages should be imported.
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 · 28 lines · 26 tokens per session scan A 9ea0198a7bb4

Subscribe to this mod's changes

fork-gap-fill-reconstruction is a skill published in the GitHub repository ychampion/cskill-agents (36 stars, last pushed 5mo ago), licensed MIT. It adds 26 tokens to every session and 394 once invoked, about $0.0001 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 2026-09-03.