Styled Speaker Prefix Diagnostic

Note

Status: implemented. DLG1107 warns when a line looks like a speaker prefix but its name is Markdown-styled (*Alice*: Hello), so the line would otherwise be silently attributed to the default speaker. Styled prefixes stay unrecognized.

Ubiquitous language

Term	Meaning
Speaker prefix	The Name @id #tag: that starts a line, parsed by SpeakerPrefixParser.
Styled speaker prefix	A would-be prefix whose name is wrapped in emphasis, so the transpiler does not recognize it.
Unattributed line	A Line with no recognized speaker; desugar fills the default speaker.
Would-be prefix	The line's leading inlines flattened to plain text, up to and including the first : outside styling.

Writer-facing behavior

Line	Result
*Alice*: Hi, **Alice**: Hi, _Alice_: Hi, ~~Ghost~~: …	DLG1107
**Bob** #gruff: What now?	DLG1107 — flattens to Bob #gruff:, which parses
A*l*ice: Hi	DLG1107 — any styling before the colon counts
`"key"?` *Alice*: Hi	DLG1107 — the condition is read first
*Alice*: Hi inside a choice option	DLG1107 — the same line builder
Alice: Hi	No warning — a recognized speaker
*Alice: hi*	No warning — the colon is inside the styling
*It was cold.*, *the great*: hi	No warning — the flattened text is not a prefix

DLG1107 — This line looks like a speaker prefix ("Alice:") but the name is styled, so it is not recognized and the line has no speaker. Remove the styling to declare the speaker.

The line still compiles unchanged.

Why it happens

LineBuilder peels a speaker only when the paragraph's first inline is plain text. *Alice*: Hello parses as EmphasisInline("Alice") + TextInline(": Hello"), so the peel stops and SpeakerPrefixParser never runs.

Detection

When the peel finds no speaker, LineBuilder calls StyledSpeakerPrefixDetector:

1. The leading run up to the first : must contain an EmphasisInline.
2. Flatten the leading inlines to plain text up to and including the first : that sits outside any styling.
3. Run SpeakerPrefixProbe (over SpeakerPrefixParser.Prefix) on it. If it parses, styling is the only reason recognition failed: report DLG1107 over the would-be prefix, with the flattened text as the argument.

flowchart LR
    LB["LineBuilder"] -->|"peel speaker"| PEEL{"recognized?"}
    PEEL -->|yes| LINE["Line with speaker"]
    PEEL -->|no| DET["StyledSpeakerPrefixDetector"]
    DET -. "DLG1107" .-> DIAG["sink"]
    DET --> LINE2["Line, no speaker"]

Key design decisions

D1 — Reported in the transpiler, beside the other recognition diagnostics

Recognition diagnostics (DLG1101–DLG1112) come from transpiler builders; validation rules work on the desugared tree, where the styling is already gone. The architecture also forbids validation from depending on the transpiler's speaker grammar.

D2 — Syntax / Warning

The line is valid Markdown that compiles, so not an error; it is a malformed speaker-prefix surface, so Syntax beside DLG1101 rather than Style.

D3 — Probe through the real grammar

Asking "would this have parsed as a prefix?" of the actual parser keeps the warning from ever disagreeing with recognition, where a look-alike heuristic would drift.

D4 — Warn, never rewrite

Promoting a styled prefix to a speaker would drop or move the writer's styling. The warning keeps Markdown meaning and leaves the choice to the writer.

Testability

• StyledSpeakerPrefixDetectorTests build inlines directly: each styled form warns; plain prefixes, fully styled lines, styled non-names, and runs with no colon do not.
• Compiles assert the code and location for a top-level line and a choice option; the error-code reference's fixed example stays clean.