Remove FlyDSL fallback machinery from MoE tuning (FlyDSL now mandatory)

[coderfeli]

Summary

FlyDSL is now a required dependency for MoE tuning, so the FlyDSL→CK fallback machinery is dead weight. Previously the tuner recorded, alongside every winning flydsl_ config, a companion CK config tagged flydsl_fallback, and the runtime swapped it in when is_flydsl_available() was False. This PR removes that generation + consumption path and the associated _tag data.

Changes

Tuner — csrc/ck_gemm_moe_2stages_codegen/gemm_moe_tune.py (stops generating fallbacks)

• Removed FLYDSL_FALLBACK_TAG, the self._flydsl_fallbacks accumulator, the _non_flydsl_best computation, and the best_has_flydsl block that merged a CK stage1+stage2 fallback row.
• result_to_csv no longer writes a _tag column or appends fallback rows. It now just drops any legacy _tag column/rows read from older tuned files, then writes a plain deduped table.

Runtime — aiter/fused_moe.py (stops consuming fallbacks)

• Removed _flydsl_fallback_cache, get_flydsl_fallback_cfgs(), and the runtime block that substituted a fallback cfg (or dropped to default heuristics) when FlyDSL was unavailable.
• The generic _tag read-filter in get_cfg_2stages is retained as defensive backward-compat for any stale user CSV. The FlyDSL-vs-CK dispatch gates (is_flydsl1 and is_flydsl_available()) are untouched — those select the wrapper, not fallback config.

Config data

• Removed the obsolete flydsl_fallback rows (372 rows) from the 7 tuned configs that carried them: dsv3_fp4, dsv4_fp8fp4, gptoss_fp8fp4, kimik2_fp4, kimik2_fp8fp4, minimax_m25_fp4, qwen3_5_397b_fp4. Only the tagged rows were deleted; all other rows and the _tag column are left byte-identical to minimize churn.

Test

• op_tests/tuning_tests/test_online_tune.py::test_tag_filter de-hardcoded its sample tag value (still validates the retained _tag read-filter).

Behavior change

With FlyDSL mandatory, a tuned config that names a flydsl_ kernel now requires FlyDSL to be installed — there is no CK fallback substitution. If FlyDSL is absent, the FlyDSL dispatch gate is skipped as before, so a flydsl_-named config will no longer silently degrade to a CK kernel.

Testing

• python -m py_compile on both edited modules — OK.
• pytest op_tests/tuning_tests/test_online_tune.py -k tag_filter — passing.
• Repo-wide grep for flydsl_fallback — no matches remain.

🤖 Generated with Claude Code

[github-actions]

🏷️ CI Guide

Runs automatically on every PR:

• ✅ Pre-checks (submodule verification, code formatting)
• ✅ Aiter op tests (gfx942 + gfx950)
• ✅ Triton tests on MI35X (only when aiter/ops/triton/** or related paths are changed)

Extended tests (opt-in via labels):

Label	Tests
ci:triton-300x	Run an additional Triton test job on MI300X in PRs; main branch always runs both MI35X and MI300X
ci:sglang	SGLang integration tests: DeepSeek-R1-MXFP4 accuracy, Qwen 3.5 accuracy
ci:atom	ATOM benchmark: DeepSeek-R1-0528, GPT-OSS-120B
ci:atom_full	ATOM accuracy suite for PR and main models from ATOM models_accuracy.json
ci:vllm	vLLM benchmark: GPT-OSS-120B, DeepSeek-R1-0528, Kimi-K2.5
ci:all	All standard extended tests (excludes ci:atom_full)

Only add ci:atom_full for FlyDSL or Triton upgrades.
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[lalala-sh]

LGTM