# Webterm > Diagnose terminal screenshot corruption caused by incomplete terminal-state updates. Use when this capability is needed. - Skill: `tomevault-io/webterm` (Agent Skill, multi-file: 2 files) - Install (CLI): `npx skillmds@latest add tomevault-io/webterm` - Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/webterm/raw - Safety review: pending (external: skill-scanner PASS, skillspector PASS) - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: Coding & Dev Tools - Author: tomevault-io (https://skillmd.com/u/tomevault-io) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/tomevault-io/webterm --- # Screenshot Debugging Skill ## Purpose Diagnose terminal screenshot corruption caused by incomplete terminal-state updates. ## When to Use - SVG screenshots show stale or overlaid text. - Live WebSocket output looks correct but `/screenshot.svg` does not. - Issues appear with full-screen TUIs (tmux/vim/less). ## Procedure 1. **Capture terminal bytes** - Capture PTY output around the failing action. 2. **Replay into the Go tracker** - Feed bytes through `internal/terminalstate` (go-te based). - Confirm whether buffer state diverges from expected terminal behavior. 3. **Check preprocessing/filtering** - Validate DA filtering and any partial-sequence buffering logic. 4. **Check dirty/refresh logic** - Verify tracker updates happen before screenshot cache decisions. 5. **Add regression coverage** - Add a focused Go test and (when useful) fuzz corpus seed. 6. **Verify** - Run `make check` and re-test the real scenario. ## Notes - Prefer reproductions from real PTY captures over synthetic minimal sequences. - If rendering differs only in dashboard thumbnails, inspect SSE activity gating and screenshot cache TTL/invalidations. --- > Source: [rcarmo/webterm](https://github.com/rcarmo/webterm) — distributed by [TomeVault](https://tomevault.io).