New `dsl::usage` module: registry pairing each command's
entry-keyword with a `parse.usage.*` catalog key.
`matched_entry()` resolves the entry keyword from the
consumed token prefix; multi-entry families (add, drop,
show) return all matching keys.
Catalog: new `parse.usage.<command>` keys (one per command),
`parse.token.{keyword,punct,...}` vocabulary (one per
Keyword/Punct variant + token-class labels + LexError
kinds), and `parse.available_commands` for the no-prefix
fallback. Catalog grows ~60 entries.
Validator: extended KEYS_AND_PLACEHOLDERS; new completeness
test asserts every Keyword and Punct variant has its
`parse.token.*` entry.
`app::dispatch_dsl` rewritten to compose three blocks per
ADR-0021 §2: caret + structural/custom error + usage block
(or available-commands fallback per §5). Caret math fixed
to use original-input byte position rather than
trimmed-input position (the lexer no longer trims before
lexing). Three pre-existing app tests adjusted to look
across all error lines instead of `output.back()` (the
usage block is now the last line).
`dsl::usage::matched_entry` uses `<=` rather than `<` for
position comparison so custom errors raised by `try_map`
(whose span starts at the first consumed token) still
resolve to the entry keyword.
Tests: 668 passing, 0 failing, 1 ignored (650 baseline →
+18: 8 usage + 1 token-vocab completeness + 9 new
integration tests in tests/parse_error_pedagogy.rs
covering create/add/drop/show/frobulate/update/insert
cases). Clippy clean.
claude@clouddev1