t27o: refusal backlog -- every first-refusal kind above 1 % that no lane holds yet (methods, macros, item kinds, tuples, other-file names, data enums, trait impls) #10602

Goal

Every first-refusal kind above 1 % of the roadmap dogfood (#10527) is tracked. The kinds already in a lane are #10526 (Ok/Err asserts, for over &[..], &[], raw strings, line continuations; PR #10593), #10534 (integer !), #10546 (Vec, vec!, Vec::new) and #10544 (run time). This issue is the backlog for the rest, one checkbox per kind, ranked by count, so each becomes its own lane when it starts. Part of #10522.

Source of truth

First refusals of tri t27o on every tracked .rs file of t27 7496ed2, trios 483dd9ee, trinity 0770abb9, trinity-fpga 20bf4c418, 999-multibots-telegraf 6e5512881 (17,015 in total, before #10593). Re-measure with tri t27o-sweep (#10543) before starting a kind: #10593 moves some counts.

The backlog (kind, first refusals, share, the largest single reasons)

• Methods outside the std table -- 2,228 (13.1 %): iter 205, to_string 161, arg 114, contains 114, into 103, unwrap_err 82, to_vec 65, push 62, lines 57, get 57, join 53, sqrt 49. Each pure one goes into rust_std.t27 with its I/O proven against Rust; arg / path / lines on I/O types stay refused.
• Macros other than vec! -- about 380 (2.2 %): env! 72, println! 57, format! 55, include_str! 51, eprintln! 39, json! 38. format! into an out-buffer already exists for String results; the print macros stay refused (I/O).
• Item kinds -- 1,127 (6.6 %): type aliases 105, use inside a block 55, and named items that are not fns.
• Tuples -- 797 (4.7 %): ( 550, String in a tuple 57, & 53. A tuple of scalars as a struct with fields _0, _1 (as tuple structs are today).
• Names from another file -- 704 (4.1 %): env::temp_dir 50, serde_json::to_string 47, and same-crate callees. Same-crate callees can be followed through the file's mod graph; crate-external ones stay refused.
• Enum variants with data -- 476 (2.8 %).
• Trait impls other than Default -- 323 (1.9 %): std::error::Error 50 and the like.
• The cascade -- 2,248 (13.2 %): not a kind to implement, but the report should show root and cascade apart (done in tri t27o-sweep, tri t27o-sweep: t27o coverage over a tree, rows reused by the seal hashes of the converter (warm run in seconds) #10543).

Done when

Each box is either an issue with a lane or a stated refusal with its reason kept, and the dogfood document lists it.

Boundary

• This issue changes no file. Each lane it starts names its own boundary (usually rust_convert.t27, rust_std.t27, their gen files and seals), one lane at a time on rust_convert.t27.

Links

#10522, #10527, #10526, #10534, #10544, #10546, #10543.

User Scenarios

• Given the backlog of first-refusal kinds above 1 % in tri t27o-sweep, when a contributor picks a kind to address, then they open a lane issue that names its own boundary (e.g., rust_std.t27, rust_convert.t27) and the dogfood document records the kind as tracked.
• Given the dogfood roadmap document, when all seven backlog kinds are resolved, then each kind appears in the document either with a lane issue reference or a stated refusal reason, and tri t27o-sweep reports zero untracked first-refusal kinds above the 1 % threshold.

Requirements

• FR-001: Every first-refusal kind above 1 % of the roadmap dogfood MUST have a corresponding lane issue or a documented refusal reason kept in the dogfood document.
• FR-002: Each lane issue started from this backlog MUST declare its own boundary files (typically rust_std.t27, rust_convert.t27, their generated files and seals) and work on rust_convert.t27 one lane at a time.
• FR-003: The dogfood document MUST list all seven backlog kinds with their status (lane issue link or refusal reason) before this issue is considered done.

Success Criteria

• tri t27o-sweep runs and reports 0 first-refusal kinds above 1 % that lack a lane issue or documented refusal (exit 0)
• 7 kinds tracked in the dogfood document (one per backlog item: methods outside std table, macros other than vec!, item kinds, tuples, names from another file, enum variants with data, trait impls other than Default)
• Each kind's checkbox in this issue is either converted to a lane issue reference or marked with a stated refusal reason