regression CASCADE: 18 jobs newly red at 6906a3416548 (auto-filed by twatch)

• Type: regression cascade (auto-filed by Track T watcher, host borg). Untriaged. 18 jobs went red in ONE sweep — treat as ONE root cause until triage proves otherwise; do NOT fan out per-job tickets.
• Found: 2026-07-20T20:45:48Z
• Root-cause suspects in the red set: none of the known root jobs — likely a broken build or harness event

Repro (start with a suspect, or any listed job)

tools/testmgr.py --tier full --job '<job>' at 6906a3416548bb8b278512bb7afca1a534e1ee43

Newly red jobs

• test-c-conformance-riscv32#shard0/6
• test-c-conformance-riscv32#shard1/6
• test-c-conformance-riscv32#shard2/6
• test-c-conformance-riscv32#shard3/6
• test-c-conformance-riscv32#shard4/6
• test-c-conformance-riscv32#shard5/6
• test-lua-cross#src:test/lua/runner.c
• test-riscv32#src:test/ccross_args.c@1
• test-riscv32#src:test/ccross_args.c@2
• test-riscv32#src:test/ccross_double_to_int.c@1
• test-riscv32#src:test/ccross_double_to_int.c@2
• test-riscv32#src:test/ccross_entry.c@1
• test-riscv32#src:test/ccross_entry.c@2
• test-riscv32#src:test/cunsigned_div_mod_b123.c@1
• test-riscv32#src:test/cunsigned_int_arith_b121.c@1
• test-riscv32#src:test/cunsigned_int_arith_b121.c@2
• test-riscv32#src:test/cunsigned_semantics_sweep_b138.c@1
• test-riscv32#src:test/cunsigned_semantics_sweep_b138.c@2

Cascade stub: one signal for one event. Track T agent (face 2) or the owning dev track triages the root; individual tickets only for whatever remains red after the root is fixed.

Superseded 2026-07-21

Root-caused to bug-a-cfront-riscv32-byval-record-result-pxxmemmove (Track A). Cascade stub retired into that bug.