fix(llama.cpp): fall back to an even layer split when the split weights sum to zero

CLAUDE.md

@@ -675,6 +675,7 @@ Current patches:
 | `0010-server-cast-vocab-type-for-common-json.patch` | **Upstream regression from the b10585 `common_json` switch (#27511), one line.** `get_res_model_info()` (`tools/server/server-context.cpp`) builds the `GET /models` + `GET /v1/models` payload and emits `{"vocab_type", meta.model_vocab_type}` — an **unscoped enum**. `common_json_value`'s integral constructor template is `std::is_integral`-gated, which *excludes* enums, so the value binds to `common_json_value(bool)` and serialises as `true`/`false` instead of the numeric vocab type. It was correct while the alias was `nlohmann::ordered_json` (nlohmann serialises an enum as an integer), so upstream regressed it silently when they flipped the alias. The project ships this: `server-context.cpp` is compiled into `libjllama` and both routes are served by `NativeServer` — the default fat-jar `Main-Class` — in full **and** attach mode (`patches/0007`'s common route table registers them). The patch casts the value to `int` at the emit site, mirroring what `jllama.cpp` does for its own two `"vocab_type"` sites. Upstream-submittable; **not yet filed upstream**. Applies after `0002`/`0003` (same file) — numbered `0010` because `0009` is burned: it names the subprocess.h patch dropped at the b10280 bump (see the note below this table), and reusing the number would make that note read as if it were about this patch. **On every bump, check whether upstream cast the value themselves; if they did, DROP this patch rather than refreshing it** — the fail-loud applier only detects "does not apply", never "upstream already fixed this", and no test can catch a redundant carry here because `get_res_model_info` is `static` inside `server-context.cpp` and unreachable from `jllama_test`. See the `CommonJsonEnumTrap` tests in `test_json_helpers.cpp` for the mechanism the cast defends against. |
 | `0011-peg-parser-lenient-invalid-utf8.patch` | **A model that emits one malformed UTF-8 byte turns a finished generation into an HTTP 500.** The server parses *every* completion through `common_chat_parse()`; with no chat parser configured (plain `/completion`) that is the content-only fallback `content(rest()) + end()`, whose scan is `common_peg_until_parser` (`common/peg-parser.cpp`). `common_chat_peg_parse()` always parses in **lenient** mode, and that scan tolerates an `INCOMPLETE` trailing UTF-8 sequence by keeping the text before it — but the `INVALID` branch right below it returns `FAIL` unconditionally, ignoring leniency. One stray byte anywhere in the generated text therefore throws `"The model produced output that does not match the expected Content-only format"` and the request 500s even though generation completed normally (`stop processing: n_tokens = 4, truncated = 0`). The patch makes the `INVALID` branch respect `ctx.is_lenient()` exactly like the `INCOMPLETE` branch — keep the text up to the malformed byte — and adds an upstream `tests/peg-parser/test-unicode.cpp` case pinning both the lenient and the still-failing strict behavior. **Strict mode is unchanged**, which is what keeps upstream's own tests green: `tests/peg-parser/test-unicode.cpp` *does* assert `FAIL` on invalid UTF-8 through the *until* parser (a `malformed UTF-8` block with three `p.until("</tag>")` cases), but each builds a bare `common_peg_parse_context` with no `COMMON_PEG_PARSE_FLAG_LENIENT`, so the lenient-only change cannot reach them. This patch adds its case inside that same block. Found by `NativeServerAttachIntegrationTest.completion_overHttp_served`, which 500s on all six Java CI platforms. Upstream-submittable; **not yet filed upstream**. Touches only `common/peg-parser.cpp` + that test, which no other patch touches, so it is independent of `0001`/`0006`/`0007`. Runnable guard: the `ContentOnlyParseUtf8` tests in `src/test/cpp/test_utils.cpp` — unlike the upstream test they are compiled and run in CI on every platform, so a bump that drops this patch reds `C++ Tests` instead of one Java job. |
 | `0006-server-embed-native-server-jni.patch` | **Makes `server.cpp`'s `llama_server` embeddable in the JVM** so the `NativeServer` JNI bridge can run the full upstream HTTP server (WebUI included) inside `libjllama` — see "Two server modes" below. b9870 already exposes `int llama_server(int, char**)` (non-static; no `main` in the file), so the patch only adds embedded-mode support: (1) a `g_llama_server_embedded` flag + `llama_server_set_embedded()` / `llama_server_request_shutdown()` (declared in the committed `src/main/cpp/native_server_bridge.h`); (2) skips installing the process-wide SIGINT/SIGTERM handlers when embedded (they would hijack the JVM's); (3) in embedded mode parses the **forwarded** argv via `common_params_parse` instead of `common_params_parse_main` (whose `GetCommandLineW` recovery would pick up `java.exe`'s command line — the same Windows class of bug `0001` fixes). `llama_server_request_shutdown()` mirrors the SIGTERM path (invokes the installed `shutdown_handler` → `ctx_server.terminate()` unblocks `start_loop()`), giving JNI an out-of-band stop since `ctx_server` is loop-local. Applies **after `0001`** (which flips this call site to `common_params_parse_main`), so its context is the post-`0001` tree; regenerate against `0001`+source on a bump. Only touches `tools/server/server.cpp`. |
+| `0012-model-guard-zero-split-sum-and-name-the-device-index.patch` | **A GPU that reports zero free memory makes every model load fail with the unactionable `error loading model: vector`.** `llama_model_base::load_tensors` (`src/llama-model.cpp`) weights the per-device layer split by `ggml_backend_dev_memory()`'s `free`, then normalises: `splits[i] /= split_sum`. With a single device reporting `free == 0` that is `0/0` → **NaN** in every split point; NaN compares false against everything, so the `std::upper_bound` below returns the end iterator, `layer_gpu == n_devices()`, and `devices.at(layer_gpu)` throws `std::out_of_range` — whose libc++ `what()` is the bare string `"vector"`, which `llama.cpp`'s `catch (const std::exception &)` prints verbatim. Upstream's `free == 0 && total == 0` host-memory fallback does **not** fire, because `total` is `recommendedMaxWorkingSetSize` and is non-zero. **Reachable since b10618..b10797**: upstream `8c0b9cd04` ("metal : fix memory query under low-memory conditions", [#27701](https://github.com/ggml-org/llama.cpp/pull/27701)) changed `ggml-metal-device.m` to `*free = *total > cur ? *total - cur : 0`; before that clamp an over-committed device (`currentAllocatedSize > recommendedMaxWorkingSetSize`) *underflowed* to a huge `size_t`, which normalised fine, so the same precondition was harmless. That is why the `Java Tests macOS …` jobs went red at the b10792→b10797 step while every Linux/Windows job stayed green — **and why only a GPU build can fail this way at all**: `act_gpu_layers` is `devices.empty() ? 0 : …`, so with no GPU backend `devices` is empty, every layer returns early on `cpu_dev`, and the `.at()` line is unreachable. **Shape:** the two blocks are lifted out of `load_tensors` into free functions declared in `src/llama-model.h`, purely so they can be driven by a test — the failing state needs a real over-committed GPU and cannot be arranged through any public API. `llama_model_splits_normalize()` carries **the fix**: on `split_sum == 0` it `LLAMA_LOG_WARN`s and falls back to an even split (`splits[i] = float(i+1)/splits.size()`), the only neutral choice when no device can be preferred and exactly right for a single device. `llama_model_splits_select_device()` carries **the diagnostic**: it bounds-checks the index and throws a `std::runtime_error` naming the function, the offloaded layer, the device index, the split-point count **and the split points themselves** — with NaN splits that message prints `nan` and names the cause outright, which is precisely what was missing when this had to be diagnosed by reading source. **A second, backend-independent trigger reaches the same line**, found while writing this up and verified against the unfixed library: `--tensor-split` values are parsed with `std::stof` and never range-checked (`common/arg.cpp`), so `-ts 1,-1` cancels out, `split_sum` is 0 again, the split points become `[inf, -nan]`, and every layer maps one past the last device — on CUDA, Vulkan or ROCm just as much as on Metal, with no memory pressure involved. That is what makes this an ordinary upstream defect rather than a Metal edge case, and the warning names both causes rather than only the memory one. Also adds upstream `tests/test-model-split.cpp` (5 cases in upstream's `testing.h` style) + its `llama_build_and_test` registration. Touches `src/llama-model.{cpp,h}`, `tests/test-model-split.cpp` and `tests/CMakeLists.txt` — **none** of which any other patch touches, so it is independent of all of them. Upstream-submittable ("model: fall back to an even split when no device reports free memory"); **not yet filed upstream**. **Runnable guard: `src/test/cpp/test_model_split.cpp`** — a FetchContent subproject builds with `LLAMA_BUILD_TESTS=OFF`, so the upstream test above is applied-but-never-compiled here (same as `0001`'s test). That file drives the same two functions from `jllama_test`, which runs on **every** platform in `C++ Tests`, so a bump that drops this patch fails the build at link time everywhere instead of surfacing as one red macOS Java job. **Verification limit — read before assuming this can be dropped:** the *failing path* still cannot be reached without a GPU backend, so the guard pins the arithmetic (what actually broke), not the end-to-end load; the end-to-end proof is the macOS CI job. On a bump, re-check whether upstream added its own `split_sum == 0` guard (grep `split_sum` in `src/llama-model.cpp`) and **drop this patch rather than refreshing it** if they did — the fail-loud applier detects "does not apply", never "upstream already fixed this". |
 
 **`0009` was dropped at the b10280 bump.** Upstream merged
 [sheredom/subprocess.h#104](https://github.com/sheredom/subprocess.h/pull/104) — the exact fix this
@@ -1446,8 +1447,9 @@ ctest --test-dir build --output-on-failure -R "ResultsToJson"
 | `src/test/cpp/test_jni_helpers.cpp` | 56 | All functions in `jni_helpers.hpp` using a zero-filled `JNINativeInterface_` mock (incl. the `utf8_to_jstring_impl` byte-array string path: emoji byte-preservation, truncated-UTF-8 replace-not-throw) |
 | `src/test/cpp/test_tts_wav.cpp` | 2 | The in-memory WAV writer `pcm_to_wav16_bytes` in `tts_wav.hpp` (WAV header/payload + little-endian clamping) — our own code, not upstream. The Qwen3-TTS pipeline it pairs with (`mtmd_helper::gen_audio`) is entirely upstream-owned (no project-side DSP to unit-test here). The load path is additionally covered by `test_tts_params.cpp` (3 tests over `tts_params.hpp`'s `build_tts_params`, plus 2 pinning the upstream `-1` default it depends on), which pins the CPU-thread resolution whose absence used to crash the JVM on every platform — see the `TODO.md` entry for the mechanism. End-to-end coverage is `TtsIntegrationTest`, which is model-gated. |
 | `src/test/cpp/test_tts_params.cpp` | 13 | The **three** builders every hand-assembled `common_params` goes through: `build_tts_params` (`tts_params.hpp`), `build_train_params` (`train_params.hpp`) and the shared `jllama::resolve_cpu_params` (`cpu_params.hpp`). Each builder is guarded separately on purpose — testing the resolver alone does **not** cover its call sites, because `train_engine.cpp` is compiled into `jllama` only, never into `jllama_test`, and `LlamaTrainerIntegrationTest` is gated on `net.ladenthin.llama.train.model`, which no CI job sets. Without these the JVM-abort bug could regress in the trainer on every platform, unseen. |
+| `src/test/cpp/test_model_split.cpp` | 7 | The two `load_tensors()` split helpers that `patches/0012` extracts out of llama.cpp's `src/llama-model.cpp` — `llama_model_splits_normalize` (proportional split, single device, and the zero-sum case that used to produce NaN, **and the cancelling `--tensor-split` case** — `-ts 1,-1` reaches the identical line on any backend with no GPU memory pressure at all) and `llama_model_splits_select_device` (every layer maps to a real device index; malformed split points throw a message that names the function, the layer, the index and the split values instead of libc++'s bare `"vector"`). **This is the runnable guard for `0012`**: the patch also ships an upstream `tests/test-model-split.cpp`, but a FetchContent subproject builds with `LLAMA_BUILD_TESTS=OFF`, so that one is applied-but-never-compiled here. This file is the only place the two functions are linked in CI, on every platform — so a bump that drops the patch fails the `C++ Tests` build outright rather than resurfacing as one red macOS Java job. It is the one test file that includes an **internal** upstream header (`llama-model.h`, via the `${llama.cpp_SOURCE_DIR}/src` include dir added for it), which is deliberate: a signature drift should fail loudly at compile time. |
 
-**Current total: 520 tests (all passing).**
+**Current total: 527 tests (all passing).**
 
 #### Upstream source location (in CMake build tree)
 
@@ -1492,6 +1494,11 @@ so missing stubs are caught immediately rather than silently.
    - JNI helper → `test_jni_helpers.cpp`
    - Upstream result type `to_json()` → `test_server.cpp`
    - `utils.hpp` function or upstream utility → `test_utils.cpp`
+   - A function one of the local `patches/` adds to llama.cpp → its own file, e.g.
+     `test_model_split.cpp` for `0012`. Give every patch that introduces a callable a
+     guard here: upstream tests carried by a patch are **not** compiled (a FetchContent
+     subproject sets `LLAMA_BUILD_TESTS=OFF`), so this is the only place a dropped patch
+     reds CI on every platform instead of on whichever job happens to hit it.
 2. Add a `TEST(SuiteName, TestName) { ... }` block using GoogleTest macros.
 3. Rebuild: `cmake --build build --config Release -j$(nproc)`
 4. Run: `ctest --test-dir build --output-on-failure`