Show HN: Mindwalk – Replay coding-agent sessions on a 3D map of your codebase

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A visualization tool that replays coding-agent sessions on a 3D map of your codebase. A session log records what an agent did, but not how it understood the task: which parts of the repo it treated as relevant, where it explored before it acted, whether its footprint matched the scope you had in mind. Reading the raw JSONL line by line doesn't answer any of that.

Draw the repository as a night map, and play the session back as light moving through it: where the agent searched, read, and edited, the map glows - everything else stays dark. The agent's understanding of the task becomes a shape you can see at a glance.

One Go binary reads Claude Code and Codex session logs, fully local; no session data leaves your machine.

curl -fsSL https://raw.githubusercontent.com/cosmtrek/mindwalk/master/scripts/install.sh | sh
export PATH="$HOME/.local/bin:$PATH"
mindwalk

The installer verifies the binary against checksums.txt and installs to ~/.local/bin (override with INSTALL_DIR; pin a release with VERSION). Windows archives are on GitHub Releases. To build from source: make setup && make build → bin/mindwalk.

With no arguments, mindwalk scans ~/.claude/projects and ~/.codex/sessions, serves the UI on a random local port, and opens a browser:

mindwalk serve [--port N] [--no-open] [--claude-dir DIR] [--codex-dir DIR]
mindwalk open [--no-open]                    open one specific session
mindwalk build [-o out]                      write the repository citymap JSON
mindwalk trace [-o out]                      write the normalized trace JSON

Views and Controls

• Tree / Terrain views - the repo as a radial tree or a treemap plain; glow ∝ how deeply and how often a file was touched.
• Touch states - each file keeps its deepest touch: seen (moss green), read (moon white), edited (warm amber), unvisited (dark). The HUD folds friction signals - error rate, churned files, edits after the last verify - into a review strip.
• Playback deck - scrub or play the session over a bucketed histogram of the run. Bars sit on a cool/warm spectrum: observation stays cool (search, read, exec), mutation glows warm (edit, verify), so editing phases jump out at a glance.
• Timeline marks - ◇ context compactions, ○ subagent launches, › user turns; every mark is a click-to-jump target.
• Inspector - click a file to pin its visit history; click a visit row to jump the playhead to that moment.

Keyboard: Space play/pause · ← /→ step (⇧ ×10) · Home / End ends · S speed · E next edit · X next error · M next mark · ⌘B session rail.

Architecture

Two artifacts, kept deliberately separate:

• a trace - the session log normalized into an ordered stream of file-touch events (internal/adapter, one adapter per agent format);
• a citymap - a deterministic layout of the repository (internal/citymap); the same tree always produces the same map, so replays are comparable across sessions.

A local Go server (internal/server) joins the two and serves the React/Three.js frontend (web). schema/ mirrors the exported JSON contracts.

Issues and pull requests are welcome. To get a working dev setup:

make setup             # install frontend dependencies
make serve             # dev server on :8765, serving web/dist from the working tree
make test              # go test + frontend build - run before sending a PR
make build             # regenerate embedded assets and bin/mindwalk

Ground Rules

See AGENTS.md for the full architecture notes:

• Keep the boundaries: adapters don't know about rendering, citymap generation doesn't depend on playback, the server just connects the two.
• Keep Go code gofmt-ed; never hand-edit internal/server/static - regenerate it with make build.
• When trace or citymap JSON shapes change, update schema/ and the relevant tests in the same change.