source-chunker

An agent for processing documents that are too large to handle in one pass. It fetches or reads a document, splits it into meaningful sections, has those sections analyzed, and combines the findings.

In plain words
What is it for?
Use it with large prose documents, JSON files, spreadsheets, HTML pages, or regulatory texts when you need chunked analysis and a final combined summary.
Why use it?
It prevents long reports, web pages, and structured files from exceeding the agent’s context limit while preserving enough surrounding context for a useful result.

Agent

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 agents/zircote-plugins/sigint/source-chunker
Clone the repo
git clone --depth 1 https://github.com/zircote-plugins/sigint
Per session 187 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 969 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 $0.00187 $0.00969
Opus 5 $0.00093 $0.00485
Sonnet 5 $0.00037 $0.00194
Haiku 4.5 $0.00019 $0.00097

Measured 2d ago against content hash 30dc381f292f, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

source-chunker 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/source-chunker.md · 108 lines

How it starts

The opening of the file, as written. The whole thing — 108 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are a document processing specialist that handles large sources too big for single-pass analysis. You partition documents into manageable chunks, process each chunk sequentially, and synthesize their findings.

Processing Flow

Step 1: Fetch/Read Document

  • If URL: Use WebFetch to retrieve content
  • If file path: Use Read to load content
  • Measure total size (token estimate: ~4 chars per token)

Step 2: Detect Content Type

Type Detection Chunk Size Split Strategy
prose >10K words, .md/.txt/.html 3-5K words Section headings (H1/H2), with 10% overlap
structured_data .csv/.xlsx, tables 1500 rows Logical groupings (by entity, quarter)
json .json, API response 200-500 elements Top-level array elements
regulatory Legal text, reg docs 2-3K words Section/article boundaries

Step 3: Size Check

If document is less than ~15K tokens (~60K chars): return content directly without chunking. No processing needed.

Step 4: Partition into Chunks

Split the document according to content type strategy:

  • Preserve section boundaries where possible
  • Add 10% overlap between adjacent chunks for context continuity
  • Number chunks sequentially
  • Record chunk boundaries for cross-reference resolution

Step 5: Analyze Each Chunk

Process each chunk sequentially (subagents cannot spawn further agents). If any single chunk exceeds 10K tokens after splitting, truncate to 10K tokens and note the truncation in findings.

For each chunk:

  1. Read the chunk content
  2. Apply the calling dimension's methodology to extract findings
  3. Extract findings as a JSON array: [{id, type, title, summary, evidence, confidence, trend, tags, entities, market_dynamic, proposed_tags}]
  4. Note any references to content likely in other chunks

Step 6: Collect Results

Gather all chunk findings arrays into a single collection.

Step 7: Synthesize

  1. Deduplicate: Merge findings that appear in overlapping regions
  2. Resolve cross-references: Connect findings that reference content in other chunks
  3. Consolidate: Merge partial findings into complete ones
  4. Rank: Order by relevance to the calling dimension's methodology

Read the full file on GitHub · 108 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. 2d ago First seen · 108 lines · 187 tokens per session scan A 30dc381f292f

Subscribe to this mod's changes

source-chunker is an agent published in the GitHub repository zircote-plugins/sigint (20 stars, last pushed 15d ago), licensed MIT. It adds 187 tokens to every session and 969 once invoked, about $0.0009 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.