reasampler/CLAUDE.md

CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

Repo identity and current state

The CMake project and binary are now named reaper_reasampler. This is ReaSampler — a per-project audio sample-bank capture tool. The MPE modules (mpe_model, mpe_view) have been removed. M0–M4 are complete: bank_model (Sample metadata + BankIndex with JSON round-trip), peaks (waveform min/max bin computation), the capture shell's offline-render path (DAW-verified spike: master-mix / time-selection capture to a project-relative bank at 32-bit float WAV, non-destructive), and persist (BankIndex ↔ project ext state: SetProjExtState/GetProjExtState under namespace "reasampler", GUID-based project identity, project-relative path resolution, Save-As bank relocation with copy semantics) are all implemented and tested. The remaining REAPER-facing shells (insert, bank_panel, actions) and the realtime backend are being built out per CONTEXT.md / PLAN.md. The discipline — pure REAPER-free testable core split from REAPER-facing shells — is preserved throughout.

CONTEXT.md is the authoritative spec and build roadmap. Read it first for any non-trivial task. Every REAPER API name cited there is correct-by-intent; verify argument order, types, and flag values against vendor/reaper-sdk/sdk/reaper_plugin_functions.h before use.

One-time submodule setup

git submodule update --init

Vendors two submodules (see .gitmodules):

• vendor/reaper-sdk — sdk/reaper_plugin.h, sdk/reaper_plugin_functions.h, SWELL headers
• vendor/WDL — WDL utilities and the SWELL cross-platform Win32 layer

Build and test

cmake -B build -S .
cmake --build build
ctest --test-dir build

Four targets:

Target	Kind	Purpose
bank_model_tests	executable	Pure unit tests for bank_model — no REAPER, no DAW.
peaks_tests	executable	Pure unit tests for peaks — no REAPER, no DAW.
capture_paths_tests	executable	Pure unit tests for capture_paths — no REAPER, no DAW.
reaper_reasampler	loadable module	The actual extension binary (.dll / .dylib / .so).

macOS / Linux: SWELL dialog resources

src/resource.rc must be pre-processed by SWELL's resgen once per platform:

php vendor/WDL/WDL/swell/mac_resgen.php src/resource.rc   # macOS; Linux reuses the output

Add the generated file to the appropriate APPLE / Linux target_sources block in CMakeLists.txt. The SWS extension build is the canonical reference for this step.

Install / reload

There is no hot-reload. Copy the built binary into REAPER's UserPlugins/ folder (Options → Show REAPER resource path) and restart REAPER. Extensions load at startup only.

Architecture: the load-bearing split

Pure core (no REAPER types, unit-testable outside the DAW):

• bank_model — Sample metadata struct + BankIndex (add/remove/query/tier/dedup-by-hash + JSON round-trip). Test it hard — it is the heart.
• peaks — waveform min/max bin computation from raw PCM. Fed a known signal, asserts envelope. Does not depend on REAPER's peak API.

REAPER-facing shells:

• capture — ICaptureBackend interface; OfflineRenderBackend (deterministic default) and RealtimeRecordBackend. Input: CaptureRequest. Output: finished file + populated Sample handed to bank_model.
• insert — placement via InsertMedia; conform-to-project-tempo is an explicit opt-in flag, never silent stretching.
• bank_panel — docked LICE-drawn grid: thumbnails, audition, multi-select, keyboard navigation.
• persist — project ext state (SetProjExtState / GetProjExtState, namespace "reasampler") ↔ bank_model JSON; project-relative path resolution.
• actions — registers the capture/placement/slot action family and routes each to the modules above.

REAPER extension contract (src/main.cpp)

• Exactly one translation unit defines REAPERAPI_IMPLEMENT — that is main.cpp. Every other .cpp includes reaper_plugin_functions.h without the define and gets extern declarations for the global API function pointers.
• REAPER dlopen()s any reaper_*.dll|dylib|so found in UserPlugins/ and calls the ReaperPluginEntry export (produced by REAPER_PLUGIN_ENTRYPOINT). rec->GetFunc resolves API pointers; rec->Register plugs extension callbacks in.
• Action registration pattern (preserve this for all new actions):
  1. rec->Register("command_id", (void*)"STABLE_FOREVER_STRING") — mints a persistent command id. Never change this string after shipping; user keybindings key off it.
  2. rec->Register("gaccel", &accel) — puts the action in the Actions list.
  3. rec->Register("hookcommand", ...) — receives every action fired; claim only your own id, return false otherwise.
  4. On unload (rec == nullptr), mirror-unregister everything with the same strings prefixed by '-'.

The load-bearing principle

Capture and placement are separate acts. Capturing audio writes a file to the bank and adds an index entry. It never puts an item in the arrange view. Placement is a distinct, on-demand action (insert module / InsertMedia). Any code path that auto-inserts a capture into the timeline violates the purpose of the tool and must be rejected in review.

Precision invariants — required before any feature ships

• Null test: a dry offline capture of a range, re-inserted at its source position, nulls to silence against the source. Ship as a verification action.
• Bit-identical repeats: identical offline capture requests produce identical files.
• Non-destructive: capture never mutates source items or tracks; the realtime backend's temp track is created and removed cleanly, and source routing is restored.
• Exact bounds: no rounding of the requested range; no added silence unless a tail is explicitly requested; channel count preserved (no silent stereo fold).
• Relative paths only in the persisted BankIndex.