M3: offline-render capture spike (master-mix / time-selection)

ICaptureBackend/CaptureRequest seam + OfflineRenderBackend driving snapshotted
RENDER_* with dither/normalize forced off for bit-identical output, RenderFailed
via filesystem check, and a pure capture_paths lib with tests. Spike action registered.

tests/test_capture_paths.cpp

@@ -0,0 +1,118 @@
+// Standalone tests for reasampler::capture_paths — no REAPER, no framework.
+// The capture shell is DAW-bound and only verifiable in REAPER; this covers the
+// one genuinely pure piece: the bank-folder / unique-name / project-relative
+// path arithmetic that feeds BankIndex::add's relative-only invariant.
+
+#include "../src/capture_paths.h"
+
+#include <cstdio>
+#include <string>
+
+using namespace reasampler;
+
+static int g_fail = 0;
+#define CHECK(cond) do { if(!(cond)) { \
+    std::printf("FAIL line %d: %s\n", __LINE__, #cond); ++g_fail; } } while(0)
+
+static void testNormalizeSlashes() {
+    CHECK(normalizeSlashes("C:\\a\\b") == "C:/a/b");
+    CHECK(normalizeSlashes("a/b/c") == "a/b/c");
+    CHECK(normalizeSlashes("a/b/") == "a/b");       // trailing slash stripped
+    CHECK(normalizeSlashes("a\\b\\") == "a/b");      // backslash + trailing
+    CHECK(normalizeSlashes("/") == "/");             // lone root preserved
+    CHECK(normalizeSlashes("") == "");               // empty stays empty
+}
+
+static void testSanitizeStem() {
+    // Safe characters survive verbatim.
+    CHECK(sanitizeStem("Kick_01.take-2") == "Kick_01.take-2");
+    // Spaces, slashes, quotes, control chars become '_'.
+    CHECK(sanitizeStem("my mix") == "my_mix");
+    CHECK(sanitizeStem("a/b\\c") == "a_b_c");
+    CHECK(sanitizeStem("q\"uote") == "q_uote");
+    CHECK(sanitizeStem(std::string("nul\0byte", 8)) == "nul_byte");
+    // Nothing usable -> stable default.
+    CHECK(sanitizeStem("") == "capture");
+    CHECK(sanitizeStem("   ") == "capture");
+    // All-separator (no alphanumeric) -> default, so the name is meaningful.
+    CHECK(sanitizeStem("...") == "capture");
+    CHECK(sanitizeStem("-_-") == "capture");
+}
+
+static void testDeriveRelativePathIsProjectRelative() {
+    BankPaths p = deriveBankPaths("C:\\Users\\d\\proj", "master mix", "1753080000");
+    // Relative path is under the fixed bank subfolder, forward-slashed, .wav.
+    CHECK(p.relativePath == "reasampler_bank/master_mix_1753080000.wav");
+    // It must NOT be absolute by any of BankIndex::add's rejection rules:
+    // no leading '/', no drive letter, no backslash, no UNC prefix.
+    CHECK(p.relativePath.find(':') == std::string::npos);
+    CHECK(p.relativePath.find('\\') == std::string::npos);
+    CHECK(!p.relativePath.empty() && p.relativePath[0] != '/');
+    CHECK(p.relativePath.rfind("\\\\", 0) != 0);
+}
+
+static void testDeriveAbsoluteDirJoinsProjectDir() {
+    BankPaths p = deriveBankPaths("C:\\Users\\d\\proj", "kick", "");
+    // Backslashes normalized; bank subfolder appended; no trailing slash.
+    CHECK(p.absoluteDir == "C:/Users/d/proj/reasampler_bank");
+    // No unique tag -> stem has no trailing "_".
+    CHECK(p.fileName == "kick.wav");
+    CHECK(p.relativePath == "reasampler_bank/kick.wav");
+}
+
+static void testDeriveHandlesTrailingSlashProjectDir() {
+    // A project dir with a trailing slash must not double up in the join.
+    BankPaths p = deriveBankPaths("/home/d/proj/", "mix", "7");
+    CHECK(p.absoluteDir == "/home/d/proj/reasampler_bank");
+    CHECK(p.fileName == "mix_7.wav");
+}
+
+static void testDeriveEmptyProjectDirFallsBackToRelative() {
+    // Defensive: with no project dir, absoluteDir is just the bank subfolder
+    // (the shell rejects the no-path case before this, but the arithmetic must
+    // not emit a leading slash that would read as absolute).
+    BankPaths p = deriveBankPaths("", "mix", "");
+    CHECK(p.absoluteDir == "reasampler_bank");
+    CHECK(p.relativePath == "reasampler_bank/mix.wav");
+}
+
+static void testDeterministicForSameInputs() {
+    // Same inputs -> same derived paths (feeds deterministic file naming).
+    BankPaths a = deriveBankPaths("C:/p", "mix", "42");
+    BankPaths b = deriveBankPaths("C:/p", "mix", "42");
+    CHECK(a.absoluteDir == b.absoluteDir);
+    CHECK(a.relativePath == b.relativePath);
+    CHECK(a.fileName == b.fileName);
+}
+
+static void testFileStem() {
+    // fileStem is the stem component of fileName (no extension). The capture
+    // backend passes fileStem directly to RENDER_PATTERN because REAPER appends
+    // the format extension itself — the backend must not re-derive or re-strip it.
+    BankPaths p = deriveBankPaths("C:/p", "master mix", "123");
+    CHECK(p.fileStem == "master_mix_123");
+    CHECK(p.fileName == "master_mix_123.wav");
+    // fileStem + ".wav" must equal fileName (the invariant the backend relies on).
+    CHECK(p.fileStem + ".wav" == p.fileName);
+
+    // No tag: stem only.
+    BankPaths q = deriveBankPaths("C:/p", "kick", "");
+    CHECK(q.fileStem == "kick");
+    CHECK(q.fileName == "kick.wav");
+    CHECK(q.fileStem + ".wav" == q.fileName);
+}
+
+int main() {
+    testNormalizeSlashes();
+    testSanitizeStem();
+    testDeriveRelativePathIsProjectRelative();
+    testDeriveAbsoluteDirJoinsProjectDir();
+    testDeriveHandlesTrailingSlashProjectDir();
+    testDeriveEmptyProjectDirFallsBackToRelative();
+    testDeterministicForSameInputs();
+    testFileStem();
+
+    if (g_fail == 0) std::printf("capture_paths: all tests passed\n");
+    else std::printf("capture_paths: %d CHECK(s) FAILED\n", g_fail);
+    return g_fail ? 1 : 0;
+}