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* spec: add DSpark speculative decoding DSpark (DeepSpec, 2026) on top of the merged DFlash drafter. It reuses the DFlash encoder/decoder graph, target feature extraction and KV-cache injection, and the verify/accept path unchanged; the draft model is a new "dspark" arch adding a low-rank Markov head (markov_w1/w2) and an optional (unused here) confidence head. No new public APIs. The proposal is the only change: the block is anchor-first (position 0 already predicts the first draft) and the decoder graph applies a semi-autoregressive, previous-token conditioned logit bias in-graph, chained per block position: logits'(i) = logits(i) + markov_w2 . markov_w1[prev(i)] prev(0) = the block's anchor token, prev(i>0) = argmax(logits'(i-1)) vectorized across all blocks in the batch; the anchors are fed through a dedicated graph input (token 0 of every block). Greedy stays lossless (verify unchanged, same as DFlash). - new arch "dspark" (llama_model_dspark : llama_model_dflash, reuses the graph, loads the markov/confidence tensors; shares the target's embed/lm_head). - Qwen3DSparkModel converter. - new spec type "draft-dspark" (common_speculative_impl_draft_dspark : common_speculative_impl_draft_dflash, overrides draft() only: submits whole anchor-first blocks and greedily reads back the biased logits). * spec: read draft block size in the dflash impl * docs: add DSpark section to speculative.md * spec: keep dspark block size read in the dspark impl * dspark : add TODOs for incomplete parts - confidence head is loaded but not used yet - confidence-scheduled prefix pruning is not implemented - the in-graph Markov chain is greedy-only - only Qwen3 backbones are supported for now (also noted in docs) * spec: fold DSpark into the DFlash arch Address review: drop LLM_ARCH_DSPARK and the dspark.block_size / markov_rank GGUF keys. A DSpark draft now converts to a DFlash GGUF; the Markov head tensors are detected by presence (like eagle3 d2t), block_size is read from the existing dflash.block_size key, and the block anchors are taken as a strided view of the decoder's token input instead of a separate graph input. * spec: add confidence-based draft pruning for DSpark The DSpark confidence head predicts per-position acceptance of the drafted block. --spec-draft-conf-min truncates the block at the first position below the threshold (default 0 = disabled). * fold the dspark impl into dflash, selected by spec type * address review comments * dspark: clean up and improve naming * update readme * remove trailing whitespace * dflash: draft full n_max blocks, defer dp.n_max to the central truncation The DSpark markov head views the draft batch as a uniform [n_seqs x block] grid, but the per-seq dp.n_max clamp could produce blocks of different sizes, silently corrupting the strided views and the resulting logits. Drop the clamp and always draft the full n_max block for every sequence: dp.n_max is already enforced by the central truncation in common_speculative_draft(), the same way eagle3 handles it. Co-authored-by: Zaire404 <3147879462@qq.com> * dflash: assert the markov head block-uniformity invariant, require the conf head With the draft batch always submitting equal-size n_max blocks, a non-divisible token count can only mean the batch was split across ubatches or a caller broke the layout - fail loudly instead of silently dropping the markov bias. The block_drafts > block_size early return stays: worst-case graph reserve passes legitimately build with n_seq_tokens > block_size. Also make conf_proj required when the markov head is present: the confidence head is part of the DSpark checkpoint format, and a missing head would otherwise leave --spec-draft-conf-min silently reading stale embeddings instead of confidences. Co-authored-by: Zaire404 <3147879462@qq.com> * dspark: fold conf_min into p_min p_min and conf_min express the same thing - the minimum predicted survival probability for a drafted position - differing only in how the estimate is obtained: token probability for regular drafters, the trained confidence head for DSpark. The DSpark readback never used p_min, so reuse it for the confidence threshold and drop the separate --spec-draft-conf-min flag. Both defaulted to 0 (disabled), so behavior is unchanged. Co-authored-by: Zaire404 <3147879462@qq.com> * dflash: note the confidence broadcast workaround Requested in review: the ggml_repeat only adapts the [1, n_tok] confidences to the n_embd-wide embd_nextn transport so that llama_get_embeddings_nextn can be reused - not a placeholder. Co-authored-by: Zaire404 <3147879462@qq.com> * cont : clarify [no ci] --------- Co-authored-by: Ruixiang Wang <wangruixiang07@outlook.com> Co-authored-by: Zaire404 <3147879462@qq.com> Co-authored-by: Georgi Gerganov <ggerganov@gmail.com>
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32 KiB