fix(whisper): extract MSVC runtime DLLs beside win32 whisper-server

[greatcoat]

Problem: Windows machines without the VC++ redistributable kill the CPU whisper-server at load with 0xC0000135 — every local dictation fails, empty stderr, before main().

Fix: Pin whisper.cpp 0.0.10 (first release bundling the MSVC runtime DLLs in its win32 zips) and extract those DLL companions beside the exe, reusing the llama/sherpa libPattern approach, now consolidated in lib/download-utils.

Important

Draft until OpenWhispr/whisper.cpp PR #6 merges and release 0.0.10 is cut — until that tag exists, any build from this branch fails to fetch the pinned release. Merging both + the release cut wait for Josh's explicit go.

Root cause

The win32 CPU whisper-server.exe links the dynamic MSVC runtime — its PE import table demands MSVCP140.dll, VCOMP140.DLL, VCRUNTIME140.dll, VCRUNTIME140_1.dll (the upstream build's CMAKE_MSVC_RUNTIME_LIBRARY=MultiThreaded static-CRT flag is a silent no-op without CMake policy CMP0091, and OpenMP links vcomp dynamically regardless) — but whisper-server-win32-x64-cpu.zip contained only the exe and download-whisper-cpp.js copied only the binary, unlike the llama/sherpa download scripts which both carry libPattern DLL companions. Nothing else provides the runtime: Electron's own copies live next to OpenWhispr.exe and are invisible to a child process in resources\bin, so on machines without the system-wide redist the loader terminates every spawn with 0xC0000135 (STATUS_DLL_NOT_FOUND).

Probe evidence (CUS-113, RCA in Titan wiki whisper-server-dll-not-found-rca.md): customer debug log debug-2026-08-17T12-23-22-137Z.log shows 14 spawns in ~8 s, each dead in ~50 ms with exit 3221225781 (=0xC0000135) across three models; PE import parse of the shipped 0.0.8/0.0.9 exes confirms the four CRT imports; zip listings confirm no DLLs shipped. Field-confirmed 2026-08-17: installing the VC++ redistributable — the only change — immediately fixed the reporting machine.

Fix

• scripts/download-whisper-cpp.js — pin 0.0.10; win32-x64 config gains libPattern: "*.dll"; DLL companions are copied into resources/bin beside the exe (identical to the llama/sherpa pattern). main() is now guarded by require.main and the config exported, so the regression test can import the script without side effects.
• scripts/lib/download-utils.js — new shared matchesPattern / findLibrariesInDir / copyLibraries; download-llama-server.js and download-sherpa-onnx.js had byte-identical private copies (whisper would have been the third), now consolidated.
• src/helpers/whisperVulkanManager.js — win32 asset gains libPattern: /\.dll$/i so the 0.0.10 Vulkan zip's CRT DLLs are extracted at runtime too; its "statically linked — no companion libs" comment was wrong about the CRT and is corrected. No-op at 0.0.9 (zip has no DLLs).

Deliberate non-changes:

• electron-builder.json — the extraResources filter already passes *.dll (the RCA's claim it blocks DLLs was stale on this point); no change needed.
• cleanupFiles — already spares libraries (isLibrary guard) and only touches the whisper-server prefix; verified, untouched.
• whisperCudaManager/whisperVulkanManager tag bumps to 0.0.10 + digests — the sha256 digest map can only be filled after the 0.0.10 assets exist; follow-up commit once the release is cut. CUDA's existing libPattern already extracts all zip DLLs, so it needs only the tag+digest bump.
• NTSTATUS exit-code decoding, spawn circuit-breaker, app-version in debug header — separate hardening PRs (nice-to-haves from the RCA), not packaging.

Tests

• RED (before the fix): test/scripts/downloadWhisperCpp.test.js fails — BINARIES["win32-x64"].libPattern is undefined, tag asserts '0.0.8' !== '0.0.10', copyLibraries is not a function.
• GREEN: all 4 new tests pass; full suite npm test: 2094 tests, 1923 pass, 0 fail (170 skipped = known Electron-ABI better-sqlite3 local skips).
• Packaged-app PE evidence + clean-Win10-VM RED/GREEN (0xC0000135 repro on current build → transcription on patched build) run once a 0.0.10-based build exists; tracked before release.

Provenance

RCA: Titan wiki/areas/engineering/whisper-server-dll-not-found-rca.md · Linear CUS-113 · customer thread 1a00fc15dfac3569 (Brian, Win10, free tier) · companion CI fix: OpenWhispr/whisper.cpp#6

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