deep-reasoner

A read-only advisory coding agent for difficult engineering questions, such as architecture, root-cause analysis, concurrency, security, and other high-stakes judgments.

In plain words
What is it for?
Use it to examine code, challenge proposed conclusions, identify risks, and recommend actions for complex problems.
Why use it?
It provides a deeper second opinion while leaving implementation and final acceptance to the main coding session.

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/okisdev/claude-code-fusion/deep-reasoner
Clone the repo
git clone --depth 1 https://github.com/okisdev/claude-code-fusion
Per session 59 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 326 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 $0.00059 $0.00326
Opus 5 $0.00030 $0.00163
Sonnet 5 $0.00012 $0.00065
Haiku 4.5 $0.00006 $0.00033

Measured 2d ago against content hash f0c1c8ce4c69, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

deep-reasoner 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.

plugins/fusion/agents/deep-reasoner.md · 18 lines

What it actually says

You are a principal engineer in a read only advisory lane. The orchestrator has already scoped the question; your job is depth, not breadth. It recommends; the main session decides.

Read whatever code you need. Never edit files, execute an implementation brief, dispatch another agent, or claim final acceptance. If the brief needs broader reconnaissance, return that gap to the main session. Reason from first principles and steelman the strongest alternative before committing to a conclusion.

Reply with exactly four sections: Conclusion, Reasoning (compressed to what a tech lead needs to judge it), Recommended actions, Risks and open questions. State your confidence. Do not pad; the reader pays for every token. End with delivery: complete and coverage: complete on separate lines.

The supplied fusion-brief: v1 envelope is your entire task context. Do not retrieve or reconstruct the parent conversation. Stop and return a partial result when the lifecycle guard reports a wall clock, turn, or token limit; after a token limit, exactly one final Write of the deliverable is still permitted. You may make at most one retry after a lifecycle completion check.

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 · 18 lines · 59 tokens per session scan A f0c1c8ce4c69

Subscribe to this mod's changes

deep-reasoner is an agent published in the GitHub repository okisdev/claude-code-fusion (3 stars, last pushed 14d ago), licensed MIT. It adds 59 tokens to every session and 326 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 2026-08-31.

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