docs: replace the opaque (A4:) and (B11:) task codes in rustdoc with the (issue #NNN) convention #1234

Doc comments and code comments carry internal task codes ((A4), (B11)) that mean nothing to readers of the rendered rustdoc or of the source, while the rest of the codebase consistently references issues as (issue #NNN).

Evidence

Refreshed against main at afa92b656 (2026-09-02): grep -rn "(A4)\|(B11)" src/ returns 32 sites in 16 files, not the six the issue was filed with. Eight of them are rustdoc /// lines that reach the rendered documentation; the other 24 are plain // comments (including test comments and one section banner) that carry the same opaque codes.

Rustdoc (///) sites, the original scope of this issue:

• src/server/cli_input.rs:562: /// (A4): path to a YAML weight-load surgery configuration.
• src/server/config.rs:854: /// (B11): server-wide KV cache mode.
• src/server/startup.rs:440: /// (B11): resolved KV cache mode for per-sequence cache
• src/server/startup.rs:530: /// (A4): resolved path to a YAML weight-load surgery
• src/server/model_worker.rs:111: /// (B11) / server-wide KV cache quantization mode.
• src/models/sanitize_tests.rs:1290: /// (A4): when the CLI installs an active pipeline via
• src/models/sanitize_tests.rs:1344: /// (A4): explicit transform argument takes precedence
• src/lib/mlxcel-surgery/src/config.rs:237: /// Used by: future CLI wiring (A4), mlxcel surgery validate (A4),

Plain // comment sites carrying the same codes (24): src/bin/mlx_server.rs:2111,2620,2650; src/commands/serve.rs:443,742,773; src/commands/serve_tests.rs:215; src/commands/generate_tests.rs:619; src/server/cli_input.rs:371,848,1171; src/server/cli_input_tests.rs:201,227,1356,1570; src/server/startup.rs:1575; src/models/sanitize.rs:1652; src/models/sanitize_tests.rs:751,835,947; src/loading/vlm.rs:322; src/main_tests.rs:406; src/cli/turbo_args.rs:185 (a section banner); src/lib/mlxcel-surgery/tests/interpolate_integration.rs:146.

The established convention elsewhere is (issue #NNN), e.g. src/backend/mod.rs:134 and src/downloader/mod.rs:184.

Suggested fix

Drop the (A4): / (B11): prefixes, or replace them with the matching (issue #NNN) reference if one exists. Treat the 24 plain-comment sites the same way in the same change: a reader of the source hits the same opaque code, and a partial cleanup leaves the grep in the acceptance criteria red. Comment-only edits, no code changes.

Acceptance criteria

• No (A4) or (B11) codes remain in doc comments (grep -rn "(A4)\|(B11)" src/ over doc comments returns nothing)
• Each edited doc comment reads as a complete sentence in rendered rustdoc
• The plain // comment sites listed above are cleaned in the same change, so grep -rn "(A4)\|(B11)" src/ returns nothing at all

Refresh log

• 2026-09-02: Refreshed against main afa92b656. Recounted the sites: 32 in 16 files (8 rustdoc, 24 plain comments) instead of the 6 listed at filing; every original line number had drifted (config.rs:451 is now :854, startup.rs:362 is now :530, cli_input.rs:430 is now :562). Added the plain-comment sites to the evidence and one acceptance criterion covering them, since the filing-time grep already spanned them. In flight: PR docs: replace opaque (A4)/(B11) task codes in code comments #1586 (opened 2026-09-02, external contributor) removes all 32 sites across 17 files; PR docs: replace opaque (A4:)/(B11:) task codes in rustdoc comments #1240 was an earlier attempt, now closed. No checkbox is checked because nothing has merged yet.