Upstream's draft/target noise-stream decoupling (vllm-project#54282) put the fork's
own mechanism inside the Gumbel kernel: `_DRAFT_NOISE_SALT` is the same
`1 << 30` offset, applied under `IS_DRAFTING`, keyed off a persistent
`sample_src_positions` buffer that the draft-input kernel advances
device-side regardless of `ADVANCE_DRAFT_POSITIONS`.

Keeping `draft_gumbel_pos` on top of that would salt the draw twice, so
delete it and let the one central sampler carry the intent:

* `_sample_probabilistic_draft` forwards `sample_src_positions`
  untouched with `is_drafting=True`, and still forwards `active_rows`
  for the variable-width autoregressive path.
* `DraftModelSpeculator.sample_draft` and the DSpark/DFlash overrides
  key by the position before the sampled token, P-1, matching upstream.
* The autoregressive override's parameter takes the base class's name.

Tests follow the mechanism rather than the retired helper: the sampler
test asserts pass-through positions plus `is_drafting`, and the
rejection-sampling distribution test keys the draft draw the same way
production does.

Verified: `tools/ci/static_gate.py` reports no undeclared envs
references and no call-arg/attr-defined drift, at the same 792/139 mypy
debt count as the pre-rebase tip; the ruff F821/F811 set over `vllm`
and `tests` is identical to that tip; 4220 files parse.

Co-authored-by: OMP Agent <noreply@omp.local>
Signed-off-by: Naadir Jeewa <naadir@randomvariable.co.uk>

…ise stream from the target's (vllm-project#54282)

Signed-off-by: Giancarlo Delfin <gdelfin@inferact.ai>

…ise stream from the target's (vllm-project#54282)

Signed-off-by: Giancarlo Delfin <gdelfin@inferact.ai>

…ise stream from the target's (vllm-project#54282)

Signed-off-by: Giancarlo Delfin <gdelfin@inferact.ai>

…ise stream from the target's (vllm-project#54282)

Signed-off-by: Giancarlo Delfin <gdelfin@inferact.ai>
(cherry picked from commit fe755c8)

…roject#54282

Adapt upstream vllm-project/vllm commit fe755c8 for Jovian Judgement. Preserve compact MTP prefill outputs, MRoPE, per-token draft-logit caching, and local DFlash2/DSpark call sites. Extend BF16 proposal and fixed/clamped-position tests.

Original fix by Giancarlo Delfin; JJ adaptation and additional regression coverage by MadeBy561 with Codex assistance. Prior R25 GPU results are not fresh-head qualification.

Co-authored-by: MadeBy561 <madeby561@gmail.com>
Co-authored-by: Codex <noreply@openai.com>
Signed-off-by: MadeBy561 <madeby561@gmail.com>

…upstream vllm-project#54282

Preserve the reviewed source head 44e6766 and its contributor history.
The first parent records the ordered serving-source composition.
Whole-tree equality and installed-artifact verification are publication gates.

Review: #653
Assisted-by: OpenAI Codex
Signed-off-by: Martin Vit <martin@voipmonitor.org>

The DFlash2 selector used the same Philox noise stream as the target's
replacement draw after rejection. This conditions replacements on the rejected
proposal and changes the intended output distribution. Adapt the independent
draft stream from vllm-project/vllm#54282 (fe755c88995ad468882517b6c4bdd60138d46a3a)
to the selector's direct Gumbel call. Offset only its local RNG index, preserve
model/cache positions and greedy behavior, and install the guarded idempotent
patch in the release, development and patch-image build paths.

The pinned libr4d GDN scan's midpoint factorization clamps growing exponents
at 80. Large decay spans can erase valid contributions and final recurrent
state without producing nonfinite values. Extend the existing libr4d build
patch with a bounded FP32 recurrence for affected sequence/head pairs, using
a conservative span threshold of 128. Preserve ordinary fast-scan outputs,
the entry-point ABI, caller stream, tensor layouts and decode path. Propagate
the original launch error before launching the correction. No host readback,
synchronization or additional temporary tensor is introduced.

Add public, checkpoint-free GPU regressions for native selector/rejection
sampling and an independent FP64 GDN recurrence. Include ordinary and extreme
decays, unequal sequences, partial chunks, mixed heads, large values, both
48/16 and 24/8 head layouts, and graph replays with changed inputs. Record
compact numeric qualification evidence and document reproduction, provenance,
the need to rebuild old computed state, and remaining performance limits.
Link the correction documentation from the README.

Validation on R9700/gfx1201 with the pinned Radiance 1.0.16 image:
- Patch applies to pinned libr4d source; both scan units compile with its
  production compiler flags; sampler installation and repeat installation pass.
- At three positions with 200,000 draws per arm, shared-noise probability error
  is 0.01781-0.01953 versus 0.000965-0.001180 after correction. Target-only and
  greedy controls pass.
- Original GDN reproduces 46.4% and 82.8% output error and 100% state error
  on two extreme-decay cases. Both corrected layouts pass all 12 cases and
  three graph replays, with output error below 0.345% and state error below
  0.252% against FP64.

This commit is limited to the two numerical defects and their validation.
End-to-end throughput, distributed TP2 and repetition-rate improvements are
not claimed. The GDN correction adds prefill work that still needs workload
performance qualification. No loop guard, history recovery or serving-policy
change is included.

…nt random streams

Backport the independently qualified upstream random-stream salt so a rejected draft does not reuse its Gumbel draw for the target replacement. Preserve the declared sampling configuration rather than hiding the bias with different decoding settings.

Authenticate the affected source preimage and include CPU regressions for repeatable stream separation. Credit the upstream fix rather than treating it as a new discovery.

Provenance
Upstream PR: vllm-project/vllm#54282 (author: TheEpicDolphin).
This is an adapted backport for the pinned vLLM API.