Developer Agent Decision Logger That Captures the Why Behind AI-Generated Changes

dev tool weekend hack •• multiple requests

As AI agents generate more code, the architectural reasoning behind changes evaporates. HN developers are independently inventing AGENTS.md files and timestamped decision logs to preserve context. The gap between agent observability tools (which track what happened) and human-readable decision capture (which explains WHY it happened) is widening fast.

builder note

Start as a git hook that auto-generates a decision log entry per commit by diffing the code change against the agent transcript. The MVP is literally: what changed, what prompt produced it, what alternatives were considered, what was rejected and why. Ship it as a CLI that outputs markdown to a decisions/ directory. The git hook format lets it spread virally through repos.

landscape (3 existing solutions)

Agent observability tools (AgentOps, LangSmith, PromptLayer) capture WHAT agents did. Zero tools capture WHY in a format that helps future developers (or future agents) understand architectural intent. The HN community is building ad-hoc solutions (AGENTS.md files, timestamped markdown) which signals demand for a proper tool.

AgentOps Agent observability platform tracking traces, costs, sessions. Built for debugging agent behavior, NOT for human comprehension of architectural decisions. Data is machine-readable, not human-readable.
LangSmith Captures full reasoning traces for LangChain agents. Excellent for debugging but the output is developer telemetry, not architectural documentation. No integration with git history or code review workflows.
PromptLayer Git-like version control for prompts. Tracks prompt evolution but doesn't connect prompts to the code changes they produced or the reasoning behind architectural choices.

sources (3)

hn https://news.ycombinator.com/item?id=47196582 "Recording dialog with the agent will become increasingly important" 2026-03-28
hn https://news.ycombinator.com/item?id=47196582 "AGENTS.md with prompt + summary in changelog directory per commit" 2026-03-28
other https://www.rockoder.com/beyondthecode/cognitive-debt-when-v... "Architectural choices vanish into chat logs" 2026-02-20
AI-agentsdeveloper-experiencedocumentationcontextgit