Stand up the unified-grammar tree walker alongside the existing
chumsky parser and migrate the eleven app-lifecycle commands
(quit, help, rebuild, save / save as, new, load, export, import,
mode, messages) end-to-end. The router in parse_tokens consults
the walker first; non-migrated commands still fall through to
chumsky.
Scope:
- src/dsl/grammar/{mod,app}.rs: Node enum (13 kinds), Word /
IdentSource / HintMode / HighlightClass / ValidationError /
CommandNode types, REGISTRY of the eleven app commands.
- src/dsl/walker/{mod,driver,context,outcome,lex_helpers}.rs:
scannerless byte-level walker, per-node-kind dispatch with
Choice/Seq/Optional backtracking, WalkContext (Phase B-D
schema fields stubbed), WalkOutcome with Match/Incomplete/
Mismatch/ValidationFailed.
- src/dsl/parser.rs: try_walker_route() runs first in
parse_tokens; bridge converts WalkOutcome to ParseError
preserving catalog wording (mode.unknown / messages.unknown
surface verbatim via friendly::translate). Legacy
try_parse_app_path_command deleted; chumsky's bare-keyword
app branches remain unreachable until Phase F sweep.
Walker design choices worth noting:
- mode <value> / messages <value> use Choice(Word, Word, Ident)
so known keywords appear in the expected-set; the trailing
Ident catch-all funnels unknown values into the friendly
validator that always errors with the catalog wording.
- save / save as is one CommandNode (Optional(Word("as"))) -
closes the round-5 "save Tab can't offer as" limitation
structurally.
- Path-bearing UX shipped per ADR-0024: BarePath terminates at
whitespace; paths with spaces use the (not-yet-wired) quoted
form. Existing tests pass on the new shape.
Tests:
- 28 new walker-specific tests in dsl::walker::tests covering
every app-lifecycle command, friendly-error wording for
mode/messages unknown values, trailing-garbage detection,
whitespace tolerance, and routing fall-through.
- Total: 805 passed, 0 failed, 1 ignored (was 777 / 1).
- cargo clippy --all-targets -- -D warnings clean.
claude@clouddev1