# Handoff — 2026-08-31 — Markdown, JavaScript, HTML and shell colouring

## State

**Tickets 0009, 0013 and 0014 are done and green**, on branch `feature/new-syntaxes`, **uncommitted**. Shell was asked for in the same breath and has no ticket.

The editor now colours six languages. Recognition is by extension, falling back to a shebang for a shell script with no extension.

- New scanners: `markdown.go` + `markdown_inline.go`, `javascript.go`, `html.go`, `bash.go`. A shared `scanner.go` holds `lineScanner`, `scanLines` and the helpers; **the TOML scanner was ported onto it** and its 24 tests stayed green throughout.
- Five new classes and theme keys — `heading`, `tag`, `attribute`, `emphasis`, `link` — set in all three shipped themes.
- `internal/syntax` at 96.0 % with 180 tests. Whole suite green under `-race`. Quality gate **PASS** after one round: 0/0/0, complexity 1389.
- Docs: a new `reference/languages.md` per language stating each scanner's exact boundary, plus a rewritten section in `explanation/colouring-and-completion.md`.
- **Verified in a real terminal** for all four new languages by rendering the editor through the project's own VT emulator and reading back each run's foreground colour.

Earlier the same day, PR #4 merged the project tree.

## In flight

Nothing. Finished through Phase 8.

## Next steps

1. **Commit and open the PR.** `feature/new-syntaxes` is the branch.
2. **Look at a long real file in each language.** The verification used four short files. A 500-line HTML page or a big shell script is where a scanner that is quadratic or that mis-carries state would show.
3. **Tickets.** 0002, 0003, 0007, 0009, 0013 and 0014 are all implemented and all still `state: open`.

## Open questions / blockers

- **The stated omissions are choices, not gaps**, and each is documented in `docs/*/reference/languages.md`: JavaScript regex literals, shell heredocs, JavaScript inside `<script>`, and the language of a Markdown fence. Any of them can be added later; all four need something the current design deliberately lacks — either a token of look-behind, or one scanner reaching into another.
- **Third-party themes lose the five new keys.** They fall back to `default`, so Markdown is readable but its headings, emphasis and links are not distinct. Nothing warns about it. If that matters, a "theme is missing keys" report would be a small feature.
- **CSS is not coloured**, and `<style>` therefore looks like text. It was not asked for; it would be the natural seventh.

## Watch out for

- **`emit` drops empty spans, so never derive a span's start from the scanner's position after a helper has moved it.** This has now bitten twice, in different shapes: the TOML scanner patched `spans[len-1].Start` and corrupted the *previous* span; `finishTemplate` called `runToBacktick`, which ran the position to the end of the line, and then asked `takeRest` to colour what was left — nothing. Pass the start in as a parameter. `takeTemplateFrom` and `finishMultilineFrom` are the shapes to copy.
- **The theme completeness test only constrains `turbo-classic`.** `turbo-dark` and `borland-light` both inherit from it, and inheritance is resolved at parse time into the theme's own map, so `Defines` returns true for an inherited key. I removed `syntax.heading` from `turbo-dark` to check the test bit, and it passed. Delete the key from `turbo-classic` to actually test it.
- **Colour clashes are invisible to the test suite.** `syntax.link` was set to the same lime as `syntax.string` in `turbo-classic`, making a Markdown link identical to an inline `code` span. Everything passed. Render the editor through `internal/terminal` and read back the foreground of each run — the throwaway program under `/tmp/render/main.go` in that session did it, and rebuilding it is a few minutes.
- **A hyphen must be able to start a word in shell**, or every `-euo` is a minus followed by a command. `startsAnOption` handles it; a "simplification" that drops it breaks every script.
- **Test names collide across scanner files.** `TestAnUnterminatedStringIsColouredToTheEndOfTheLine` and `TestABackslashDoesNotEscapeInALiteralString` both existed for TOML already. Prefix new ones with the language.
- **`splitLines` trims a trailing `\r`**, so a CRLF file colours the same as an LF one. Do not replace it with `strings.Split(src, "\n")`.