# Annotate > Enrich a GSL decompilation (a .gsl produced by libre99gsl decompile) with runtime evidence, interactively: compile the decompilation itself, play it headlessly with libre99probe, improve symbol names and comments, and prove after every edit that the file still compiles byte-identically (libre99gsl verify). Use when asked to annotate, enrich, or explore a decompiled TI-99/4A cartridge. - Skill: `cycleaddict/annotate` (Agent Skill) - Install (CLI): `npx skillmds@latest add cycleaddict/annotate` - Raw SKILL.md: https://api.skillmd.com/api/skills/cycleaddict/annotate/raw - Safety review: pending - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: Coding & Dev Tools - Author: cycleaddict (https://skillmd.com/u/cycleaddict) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/cycleaddict/annotate --- # Annotate a GSL decompilation with runtime evidence You will enrich a decompiled `.gsl` file with meaningful names and comments **earned by actually running the program** — without changing a single byte of what the file compiles to. The `.gsl` is the single source of truth: you compile *it* and run the result. The original cartridge image is never needed — the decompiler proved byte-identity when it produced the file, and you preserve that identity edit by edit, so the compiled decompilation *is* the program. ## The interactive loop This is a conversation, not a batch job: 1. The user starts the flow with the `.gsl` path and whatever they already know — what the program is, where companion media lives (data disks), what to focus on, standing orders ("don't touch the sound driver"). Those in-prompt hints are the steering channel; there is no hints file. 2. You run a **pass**: as much annotation as the evidence supports. Don't interrupt the pass with questions unless you are truly blocked (a missing file, an ambiguous instruction) — prefer finishing and asking in the report. 3. You end the pass with the **report** (Step 5): coverage and its delta, renames with evidence, discoveries, what stayed unreached, and exactly what hint or media would unlock more. 4. The user replies with new hints or directions — run another pass, same conversation. They stop when returns diminish. Conversations are ephemeral; the file is not. Record every durable user-supplied fact (media paths, what the game is, standing orders) in the notes block's CONTEXT section (Step 4) so later passes — in this conversation or a fresh one — inherit them. ## The four iron rules 1. **The file must stay byte-identical.** Before the first edit, compile the pristine file into the pass baseline; after every batch of edits, verify against it: ``` ./target/release/libre99gsl compile -o /baseline.ctg --format ctg ./target/release/libre99gsl verify /baseline.ctg --format ctg ``` If verify fails, fix or revert the batch before doing anything else; never finish with a failing verify. (The check is name-blind — renames and comments cannot break it; touching real statements or data can. Byte-identity is transitive: the decompiler proved the file against the original cartridge, each pass proves itself against the previous state, so the chain back to the original never breaks.) 2. **Addresses are ground truth — never remove them.** Every declaration keeps its `@ 0xNNNN`, every function header keeps its `// >NNNN:` line. Renamed **functions keep the address suffix** (`sub_C41E` → `store_menu_C41E`); **variables may take plain names** (`b_8340` → `party_gold`) because their declaration pins the address — the same convention the decompiler's own static renames use. Never edit the `format`/`title` declarations. 3. **Evidence discipline.** Rename only what you *observed*: the trace or coverage placed execution there, the screen showed it, memory changed in step with it. Prefix comments `observed:` for session facts and `likely:` for inference. No evidence → no rename; a plausible guess is worse than an honest `sub_XXXX`. 4. **Copyright.** Decompilations of commercial cartridges — and everything derived from them (the enriched `.gsl`, the compiled baseline, evidence files, session scripts) — stay **outside this repository**. Never commit them; keep them next to the `.gsl` or in scratch space. ## Step 0 — set up - `cargo build --release -p libre99-probe -p libre99-gsl` - Read the `.gsl` header comment (the first ~60 lines) and the **tail** of the file: an existing `EXPLORATION NOTES` block means this is a later pass — read it fully (especially CONTEXT) and build on it. Passes are cumulative; never discard earlier sessions, renames, or notes. - Pick a scratch directory for the baseline image, session scripts, evidence dumps, and screenshots. - Compile the baseline (iron rule 1) **before any edit**, and run a baseline `verify` — it must pass (if it doesn't, stop and tell the user). The baseline `.ctg` is also the image every probe session runs. ## Step 1 — index the file (don't read all of it) The file may be hundreds of KB. Grep, don't read end to end: - `grep -n '^fn ' file.gsl` → the function index: every name and `@ 0xNNNN` address. A function's byte span runs from its address to the next one's — this index is what turns trace/coverage addresses into function names. - The `// >NNNN:` headers already carry the static analysis: effects (`formats screen text`, `reads keyboard`, …), `// prints:`, `// calls:` / `// called from:`. Your job is the layer static analysis cannot reach: what the code *means* in the running program. ## Step 2 — play (the evidence loop) `libre99probe` is the control surface — `docs/PROBE.md` is the manual — and `/baseline.ctg` is the image it runs. Two driving modes, both good: - **Script replay**: keep `session-N.txt`, append commands, rerun `./target/release/libre99probe /baseline.ctg --script session-N.txt`. The emulator is deterministic, so the script *is* the session — and the replayable proof of every claim you make from it. - **Checkpoints**: `save`/`load` state files to branch-explore (checkpoint before a menu, try option 1, `load`, try option 2) without replaying. The loop is: `screen` → decide → `press`/`type` → `settle` → repeat. For custom-font or sprite-heavy screens where the ASCII decode is unreadable, `shot file.png` and view the image. A standard opening: ``` frames 180 # power-up to the master title press space # any key → selection menu settle press 2 # the cartridge's first program settle ``` If the user named companion media, mount it (`disk 1 ` — live, no reset needed) and take the program's load path. Evidence channels, and when to use each: - `cover on` at session start and leave it on (it's cheap). At session end, `cover` for the summary and `cover save ` for the ranges. Bucketed against the Step-1 function index this yields the coverage measure: *N of M functions observed executing*. - `trace on` only around a moment — "what runs when I press B here?" — then `trace summary` / `trace save`, since the log grows fast; `trace on` restarts it. Fetches at `>6000`+ are the program's own code executing. - `peek` scratchpad ranges before/after an action to see which cells changed — the raw material for variable names (`observed: decremented each combat round`). - `audio 30` to confirm an action beeped (sound-driver attribution). - The strongest naming evidence combines channels: *function X executed while the screen said Y* (trace window + `screen` in the same moment). Plan sessions around the user's hints. Probe menus and verbs systematically — save states make it cheap to try every option of every menu. Reaching all code is intractable; make reasonable, hint-guided efforts, then *document* what was not reached and why rather than guessing. ## Step 3 — edit - **Renames**: whole-word search-and-replace across the file — declaration, call sites, and `calls:`/`called from:` cross-references all use the same spelling, and a missed site is a compile error that `verify` will catch. - **Comments**: terse and in place. Explain what the code *means* in the program ("`observed:` prints the store menu"), not what the instructions do. Use `likely:` sparingly and honestly. - Batch small (one subsystem at a time) and run `verify` after each batch, so a mistake is easy to bisect. ## Step 4 — the EXPLORATION NOTES block Maintain exactly one block comment at the very end of the file — append it on the first pass, update it (bump the pass number, merge sessions, renames, and context) on later passes: ``` // ===================================================================== // EXPLORATION NOTES — pass 2 (3 sessions) — by the /annotate skill // ===================================================================== // CONTEXT (durable facts from the user — future passes rely on these) // This is Tunnels of Doom, TI's 1982 dungeon-crawl RPG. // Data disk: /path/to/tod-data.dsk (mount DSK1; answer 2 at the // "LOAD DATA FROM" prompt). Don't rename the sound driver. // COVERAGE // functions observed executing: 212/344 (62%) // cart GROM addresses read: 18412/40960 // SESSIONS (deterministic keystroke scripts — replay to reproduce) // 1 "boot to party creation" (session-1.txt): // frames 180 / press space / settle / press 2 / settle / press 1 / ... // 2 "store + combat" (session-2.txt): ... // RENAMES (one per line, with evidence) // sub_C41E -> store_menu_C41E observed: executed while screen read // "GENERAL STORE"; draws its menu // b_8340 -> party_gold observed: fell 250->175 on a purchase // UNREACHED (and why) // >D9A2->DB00 cassette error path — needs a mid-load cassette fault // NEXT HINTS (what would unlock more) // - a data disk in DSK1 would open everything past "LOAD DATA FROM" ``` The block doubles as the machine-readable record: scripts verbatim, one rename per line, the user's durable context. It is how the next pass — and the user — knows where things stand. ## Step 5 — report, then iterate - Final `verify` must print `verify OK` — quote that line in your report. - Report to the user: coverage numbers (and their delta from the previous pass), the rename count with the two or three best examples, notable discoveries about how the program works, what stayed unreached, and — phrased as questions they can answer in their next message — exactly what hints, media, or focus areas would make another pass worthwhile. - If the user replies with more, fold their answers into CONTEXT and run the next pass.