why

A command that explains why a piece of code exists by tracing its history. It can connect the relevant commit to a GitHub pull request, JIRA ticket, and review discussion.

In plain words
What is it for?
Use it on a file or line to get a quick or thorough explanation, or request machine-readable JSON and adjust the history walk with command options.
Why use it?
It replaces the manual process of running git blame and following repository links to reconstruct the code's background.

Command

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 commands/shiyas1331/devkit/why
Clone the repo
git clone --depth 1 https://github.com/shiyas1331/devkit
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 765 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 $0.00765
Opus 5 $0.00030 $0.00382
Sonnet 5 $0.00012 $0.00153
Haiku 4.5 $0.00006 $0.00076

Measured yesterday against content hash 09b5ca832200, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

why 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 yesterday.

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.

commands/why.md · 84 lines

How it starts

The opening of the file, as written. The whole thing — 84 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Why does this code exist? — router

This is a thin dispatcher. The picker fires when there's no flag; otherwise the command parses input and delegates to a sub-command. The full pipeline lives in commands/why/default.md — the canonical body that other sub-commands reference.

Response format — always:

  • Start with the answer (one paragraph). The first sentence is the "why."
  • Be direct. No marketing language.

Input

$ARGUMENTS

Routing rules — apply in order

1. Picker fires when no flag is present

Trigger:

  • $ARGUMENTS is empty, OR
  • $ARGUMENTS contains only a target (file:line / file / file:start-end) with no --* flag

Use AskUserQuestion:

question: "How deep should I go?"
header: "Depth"
multiSelect: false
options:
  - label: "Quick why (~10s answer)"
    description: "One paragraph + sources + walk summary."
  - label: "Thorough drilldown"
    description: "Adds PR description, key review-thread debate, secondary edits."
  - label: "JSON output"
    description: "Machine-readable for tooling."
  - label: "Custom (more flags)"
    description: "Combine flags like --max-walk=10 or --depth + --json. Pick this then paste the full command."

If $ARGUMENTS has no target yet, prompt: "Target? (e.g. apiClient.ts:188, or apiClient.ts:120-150 for a range)".

Map answer → sub-command and re-invoke:

Choice Re-invoke
Quick why /devkit:why <target> (default sub-command)
Thorough drilldown /devkit:why <target> --depth=thorough
JSON output /devkit:why <target> --json
Custom (prompt user for the full command)

2. Help token → delegate to help sub-command

Trigger: $ARGUMENTS contains --help, -h, or ? as a standalone token.

Delegate to commands/why/help.md.

3. Flag-based input → delegate to flag sub-command

Pattern Delegate to
<target> --depth=thorough commands/why/thorough.md
<target> --json commands/why/json.md
<target> (bare, no flag) commands/why/default.md

Read the full file on GitHub · 84 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. yesterday First seen · 84 lines · 59 tokens per session scan A 09b5ca832200

Subscribe to this mod's changes

why is a command published in the GitHub repository shiyas1331/devkit (4 stars, last pushed 1mo ago), licensed MIT. It adds 59 tokens to every session and 765 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.