Phase 31: add CLAP, VST2 and VST3 mono effect hosting

docs/ROADMAP.md

@@ -860,6 +860,45 @@ byte-identical binaries and repacks; and binary manifest/hash/relocation checks.
 No public release, tag, version bump or system install is performed. Physical
 qualification and the Phase 29 graph timing alert remain documented limitations.
 
+## Phase 31 — CLAP, VST2 and VST3 Plugin Loading
+
+### Goal
+Load trusted Linux CLAP, VST2 and VST3 audio effects through the graph and GUI,
+with explicit lifecycle, format compatibility and realtime ownership contracts.
+
+### Tasks
+- Review and pin redistributable ABI headers and license notices; keep C99 adapters.
+- Add explicit format probing and compatible mono float32 effect initialization.
+- Integrate processing, immutable plans, retirement and failure rollback.
+- Share module entry lifetimes across overlapping instances; defer main-thread callbacks.
+- Add format/stable identity metadata with v11 migration and missing-module retention.
+- Generalize the GUI browser, insertion/replacement and identity presentation.
+- Test original fixtures for all three ABIs, partial failure cleanup, callback safety,
+  save/reopen, missing dependencies and GUI lifecycle.
+- Document the initial default-configuration effect subset and unsupported extensions.
+
+### Acceptance criteria
+- Compatible fixtures for all three formats render exact expected audio in graphs.
+- Failed loading/identity/layout/initialization retains the current project/plan.
+- Loading and reclamation remain off the audio callback, with bounded host processing.
+- Project files preserve identity and missing references without executing plugins.
+- Core/GUI builds, regressions, sanitizers and release installation checks pass.
+
+### Implementation status
+Implemented in C99 with pinned permissive ABI headers, shared entry lifetimes,
+CLAP main-thread scheduling, graph/GUI integration and v11 plugin identity.
+Normal/minimal builds, core and GUI plugin fixtures, live JACK/workflow,
+ASan/UBSan core and GUI checks, static analysis, staged installation and
+source/binary release checks pass. Tests include activation/start/process and
+restart errors, rejected layouts/identities, missing modules and retirement.
+GUI leak checking retains only the existing Fontconfig suppression; core checks
+use none. Only original ABI fixtures are qualified; arbitrary third-party plugins
+and physical audio remain unverified. See PLUGIN_HOSTING.md and decision 0010.
+
+The initial subset excludes instruments/events, editable modern parameters,
+opaque state/custom editors, true stereo/multichannel and latency compensation.
+These require separate future work; they are not claimed as implemented by loading.
+
 ---
 
 ## Recommended Execution Order