Clean up common/ comments and the log-ring strncpy warning

Comments must not document the past or reference plan circumstances:
drop the stale pointer to a never-created audio_correlate_layout.hpp,
the "step b" plan labels, the "carved out of reserved space" history
note, and a README pointer; reword a past-tense seqlock comment to
describe the failure mode in the present.

Replace the strncpy in log_ring_push with a bounded memcpy: same
semantics (truncate + NUL), but without the C4996 deprecation warning
on every host build.

common/include/coop/audio_correlate.hpp

@@ -15,8 +15,8 @@
 //
 // This header is the pure, headless-testable core (no devices, no WASAPI). The host downmixes the
 // two captures to mono float, calls correlate_rate(), and feeds the result into the existing rate
-// path (publish / override). audio_correlate_layout.hpp (step b) reuses these helpers to also
+// path (publish / override). correlate_format() below builds on the same helpers to also recover
-// recover channels + bit depth by trying candidate de-interleavings.
+// channels + bit depth by trying candidate de-interleavings.
 #pragma once
 
 #include <cmath>
@@ -254,7 +254,7 @@ inline RateCorrelation correlate_rate(const std::vector<float>& hook_mono, const
 	return result;
 }
 
-// --- Step (b): channels + bit-depth recovery --------------------------------------------------
+// --- Channels + bit-depth recovery -------------------------------------------------------------
 //
 // The rate step assumes the hook bytes are de-interleaved at the device channel/bit layout. When a
 // game renders a DIFFERENT layout than the device (e.g. stereo float on a 7.1 endpoint, or 16-bit

common/include/coop/audio_ring.hpp

@@ -90,10 +90,9 @@ struct AudioRingHeader
 	// Host -> hook: format-verification co-capture. While 1, the hook pushes a still-being-measured
 	// (guessed) stream's raw pre-mix bytes into the ring WITHOUT silencing the game, so the host can
 	// capture both the hook (pre-mix) and a parallel process-loopback (post-mix) of the same audio
-	// and cross-correlate them to recover the true sample rate (and, in step b, channels/bit-depth)
+	// and cross-correlate them to recover the true sample rate / channels / bit-depth from ground
-	// from ground truth instead of guessing. Inert (0) by default -- normal capture is unaffected,
+	// truth instead of guessing (see audio_correlate.hpp). Inert (0) by default -- normal capture is
-	// so it never changes the shipping no-echo path. It's a 4-byte atomic carved out of the header's
+	// unaffected, so it never changes the shipping no-echo path.
-	// reserved space; the version gate (kAudioRingVersion) rejects any layout that doesn't match.
 	std::atomic<std::uint32_t> verify_capture;
 
 	std::uint8_t reserved[36];
@@ -275,10 +274,9 @@ inline std::uint32_t audio_ring_poll_op(AudioRingHeader& h, std::uint32_t& last_
 	return out.kind;
 }
 
-// Build the per-pid audio ring name both sides agree on. Stream 0 keeps the bare
+// Build the per-pid audio ring name both sides agree on. Stream 0 uses the bare
-// coop_audio_<pid> name (backward compatible / the single-stream case); additional
+// coop_audio_<pid> name; additional streams append _<index> (coop_audio_<pid>_1,
-// streams append _<index> (coop_audio_<pid>_1, _2, ...). The host captures every
+// _2, ...). The host captures every render stream into its own ring and mixes them.
-// render stream into its own ring and mixes them.
 inline std::wstring audio_ring_name(unsigned long target_pid, unsigned index = 0)
 {
 	std::wstring name = std::wstring(kAudioRingPrefix) + std::to_wstring(target_pid);

common/include/coop/log_ring.hpp

@@ -9,6 +9,7 @@
 // ever falls a whole ring behind (fine for diagnostics). POD + version-locked.
 #pragma once
 
+#include <algorithm>
 #include <atomic>
 #include <cstdint>
 #include <cstring>
@@ -94,15 +95,16 @@ inline void log_ring_push(LogRing& r, std::uint32_t pid, std::uint32_t level, st
 	LogRecord& rec = log_ring_records(&r)[idx % r.capacity];
 	// Seqlock write. Mark the slot in-progress (seq 0) and fence BEFORE touching the record, so a
 	// consumer still reading the slot's previous occupant sees seq change and bails instead of reading
-	// half-overwritten text; publish the new generation only after the text is fully written. Without
+	// half-overwritten text; publish the new generation only after the text is fully written. A single
-	// this the consumer's single seq check passed before the read, so an overwrite mid-read tore it.
+	// seq check before the consumer's copy would miss an overwrite that starts mid-read.
 	rec.seq.store(0, std::memory_order_relaxed);
 	std::atomic_thread_fence(std::memory_order_release);
 	rec.pid = pid;
 	rec.level = level;
 	rec.millis = millis;
-	std::strncpy(rec.text, text, kLogMsgLen - 1);
+	const std::size_t len = std::min<std::size_t>(std::strlen(text), kLogMsgLen - 1);
-	rec.text[kLogMsgLen - 1] = '\0';
+	std::memcpy(rec.text, text, len);
+	rec.text[len] = '\0';
 	std::atomic_thread_fence(std::memory_order_release);
 	rec.seq.store(idx + 1, std::memory_order_relaxed); // publish: generation idx is ready
 }

common/include/coop/tone_analysis.hpp

@@ -11,7 +11,7 @@
 //
 // Header-only, no Windows / no audio-device dependency, so it is unit-tested with
 // synthesized adversarial signals (tests/tone_analysis_test.cpp) and reused by the
-// coop_audio_validate tool. See README "Lessons learned" / the audio notes.
+// coop_audio_validate tool.
 #pragma once
 
 #include <algorithm>