[leoafarias]

Summary

The generator had four copies of its string-literal helper (shared inference, schema-first emitter, class-first emitter, class-first graph builder). They escaped quotes, backslashes, and $, but wrote raw line terminators into single-quoted Dart source. A @Pattern, discriminator, or key value containing a newline or carriage return therefore generated invalid code. Other control characters were legal but unreadable.

• Replace the four copies with one dartStringLiteral helper that also writes C0 control characters and U+2028/U+2029 as \uXXXX. DEL (0x7F) is legal in Dart strings and stays raw.
• string_literal_test.dart round-trips several values through the Dart parser and checks that line terminators are escaped.
• inference_literal_test.dart exercises the public shared-inference interface with four cases. The LF/CRLF case fails without the fix; the others lock in existing escaping and the new \uXXXX output.

Scope change

This fix now ships in Ack 1.7. The branch is one commit on the 1.7 stack (base: #174) instead of the older main snapshot, and it covers every generator literal, not only shared inference. The test file uses formatter output, which fixes the earlier CI formatting failure. The changelog entry is in the 1.7.0-beta.1 section; published history is untouched.

It stays independent of #163, which remains 2.0. Unpaired UTF-16 surrogates in annotation values are not handled; that is a possible follow-up.

Validation

Validated locally on the combined 1.7 tree (feat/ackmodel-class-description, head 2d632300), which includes every PR in the stack:

• dart run melos run test --no-select passed. Strict analysis (--fatal-infos) found no issues in all seven packages. Tests passed: ack 1,311, ack_generator 347, ack_firebase_ai 98, ack_mcp_dart 63, ack_json_schema_builder 51, ack_annotations 8, plus the root and example suites.
• A clean regeneration (delete *.ack.dart/*.g.dart, then melos run build) reproduced the committed output exactly.
• dart scripts/api_check.dart 1.6.2 reported no breaking changes in any of the six packages. It cannot inspect generated consumer code, so it does not flag the typed copyWith getter; the ack_generator changelog documents that under Breaking.
• dart scripts/publish_dry_run.dart reported 0 warnings for all six packages. verify_release_tag v1.7.0-beta.1 --skip-ancestry, dart format --set-exit-if-changed, and git diff --check passed.
• No feat(ack): support Draft 2020-12 runtime import and export #171 or feat(generator): generate models from Draft 2020-12 schemas #167 commit is an ancestor of the stack.
• Each PR was reviewed by an Opus 5.5 agent (AI-slop review, adversarial change review, and a description check). The blocking findings (constrained Set codegen in chore(release): prepare Ack 1.7.0-beta.2 #168, schema import prefix in feat(generator): add a static schema shorthand to AckInfer models #174) and the non-blocking fixes are included.