hotfix(bash): fix main-red — bash_exit_code_lex projects from a fixed-span phrase (undefined bash_lex_rule from #5347)

[briansrls]

main is RED — this unblocks the whole tree

#5347 (bash slice 5d Exit) merged a fn bash_exit_code_lex() that calls a bash_lex_rule(...) constructor defined nowhere in the tree (bash.dag:1095). The whole-tree CI floor resolves every *_test.dag closure, so this dangling call fails resolve for bash_emit_command_test.dag and turns main RED for every open PR.

• main HEAD 0624060e90 + #5347 b9386b8bcf → failure; the commit just before Bash dissolution slice 5d (Exit — LAST emit-vocab construct): migrate ShellStmt Exit{code:Int} (renders 'exit <code>', e.g. 'exit 1'; live consumer dsl/tools/host_prelude.dag) from the serialize_bash sidecar into a v2 emit row. READ FIRST memory bash-sidecar-dissolution-arc-ownership §5d DISPATCH BR #5347 5c493fcf3e → success.

Fix (§3 single authority)

lexing.dag's LexicalPhrase is the single authority — lex rules project from the construct's fixed-spelling spans via phrase_to_lex_rules(p: phrase([...])), exactly as the bound-token sibling bash_env_prefixed_cargo_lex does. A direct rule constructor is the "authored three times that could silently disagree" anti-pattern that comment forbids.

Only the exit keyword is a fixed span; the exit code is an emit-time bound token (^bash_token_exit_code via binding_spellings), so it contributes no literal lex rule — preserving the original single-rule behavior bit-for-bit.

A tighter fix than a two-span phrase (incl. the code span): a LexicalPhrase is fixed-spelling-only by contract, so the bound code cannot be a span; a literal span for it would over-generate a spurious rule. Confirmed with the bash arc owner @warm-badger-46, who also cleared the colliding bash_lex_rule constructor in #5363.

Verified by execution

claim_batch --source-root dsl --source-root src/v2:

• bash_emit_command_test.dag now RESOLVES clean (43 modules; was resolve-FAIL)
• bash_emit_command_accepts, bash_emit_bound_words: PASS
• bash_emit_exit_code_{0,1}: PASS
• bash_emit_exit_code_1_quoted_wrong_{ne_correct,model,rejects}: PASS (discriminating RED intact)

🤖 Generated with Claude Code

[briansrls]

Superseded — #5356 merged first (01:58Z) carrying a byte-identical inline copy of this one-span bash_exit_code_lex fix, so main HEAD 028022c already contains this exact line and its CI is green. Closing as a redundant no-op (not rebase-to-empty), per coordination with the bash arc owner @warm-badger-46 who tracked all three racing fixes. Main-red resolved.