docs(paged): reject persistent gate fusion shortcut

Assisted-by: Codex:gpt-5

docs/superpowers/plans/2026-07-01-persistent-gate-fusion-phase43.md

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+# Persistent Gate Fusion Phase43 Implementation Plan
+
+> **For agentic workers:** REQUIRED SUB-SKILL: Use superpowers:subagent-driven-development (recommended) or superpowers:executing-plans to implement this plan task-by-task. Steps use checkbox (`- [ ]`) syntax for tracking.
+
+**Goal:** Determine whether the Phase42 persistent/load-time F32 combined gate projection can be implemented as a low-conflict GB10 shortcut.
+
+**Architecture:** Inspect the Qwen35MoE tensor load and graph consumption paths, then decide whether to implement, reject, or rescope before source changes. This phase is a feasibility gate, not a production patch.
+
+**Tech Stack:** llama.cpp model loader, Qwen35MoE graph builder, GGUF tensor metadata, LocalAI parity docs.
+
+---
+
+### Task 1: Inspect Gate Tensor Source Paths
+
+**Files:**
+- Read: `/home/mudler/_git/llama.cpp/src/models/qwen35moe.cpp`
+- Read: `/home/mudler/_git/llama.cpp/src/llama-model-loader.cpp`
+- Read: `/home/mudler/_git/llama.cpp/src/llama-model.cpp`
+- Read: `/home/mudler/_git/llama.cpp/src/llama-model.h`
+
+- [x] **Step 1: Locate tensor creation**
+
+Observed in `src/models/qwen35moe.cpp`:
+
+```cpp
+layer.ffn_gate_inp = create_tensor(tn(LLM_TENSOR_FFN_GATE_INP, "weight", il), { n_embd, n_expert }, flags);
+layer.ffn_gate_inp_shexp = create_tensor(tn(LLM_TENSOR_FFN_GATE_INP_SHEXP, "weight", il), { n_embd }, flags);
+```
+
+- [x] **Step 2: Locate tensor consumption**
+
+Observed:
+
+```cpp
+build_moe_ffn(cur, model.layers[il].ffn_gate_inp, ...);
+ggml_tensor * shared_gate = build_lora_mm(model.layers[il].ffn_gate_inp_shexp, cur);
+```
+
+- [x] **Step 3: Locate loader support for persistent derived tensors**
+
+Observed:
+
+```text
+create_tensor(...) duplicates tensors from GGUF metadata.
+create_tensor_as_view(...) can create views of existing GGUF tensors.
+Backend buffers are allocated from loader contexts before load_all_data(...).
+No existing helper creates a new persistent derived weight from two already-loaded tensors.
+```
+
+### Task 2: Make Feasibility Decision
+
+**Files:**
+- Modify: `backend/cpp/llama-cpp-localai-paged/docs/GB10_PARITY_PHASE0_RESULTS.md`
+- Modify: `backend/cpp/llama-cpp-localai-paged/docs/VLLM_PARITY_LEVER_MAP.md`
+- Modify: `backend/cpp/llama-cpp-localai-paged/docs/PARITY_HANDOFF.md`
+- Create: `docs/superpowers/plans/2026-07-01-persistent-gate-fusion-phase43.md`
+
+- [x] **Step 1: Reject graph-time fallback**
+
+Decision:
+
+```text
+Do not use ggml_concat() at graph time; Phase39 already rejected it because concat_layout is measurable in serving.
+```
+
+- [x] **Step 2: Reject Qwen-only loader hack**
+
+Decision:
+
+```text
+Do not read both tensors back to host, allocate an extra backend weight buffer, and patch layer pointers after load.
+That would create high conflict surface across mmap, offload, split buffers, MTP blocks, and state lifetime.
+```
+
+- [x] **Step 3: Record no-go**
+
+Decision:
+
+```text
+Persistent/load-time fused gate projection is not a small GB10 shortcut.
+It requires either a GGUF-exported combined weight or a general derived-weight facility in llama.cpp.
+```
+
+### Task 3: Verify and Commit
+
+**Files:**
+- Modify: `docs/superpowers/plans/2026-07-01-persistent-gate-fusion-phase43.md`
+
+- [x] **Step 1: Verify docs**
+
+Run:
+
+```bash
+git diff --check
+git status --short
+```
+
+- [x] **Step 2: Commit**
+
+Run:
+
+```bash
+git add backend/cpp/llama-cpp-localai-paged/docs/GB10_PARITY_PHASE0_RESULTS.md \
+  backend/cpp/llama-cpp-localai-paged/docs/VLLM_PARITY_LEVER_MAP.md \
+  backend/cpp/llama-cpp-localai-paged/docs/PARITY_HANDOFF.md
+git add -f docs/superpowers/plans/2026-07-01-persistent-gate-fusion-phase43.md
+git commit -m "docs(paged): reject persistent gate fusion shortcut" -m "Assisted-by: Codex:gpt-5"
+```