release: 0.0.85 — descriptor grammar v2, xpkg parse, scan_overrides, ddi audit, index floor

Version bump (mcpp.toml + MCPP_VERSION) and docs: [scan_overrides] section
in 05-mcpp-toml.md. One-time compatibility note for release notes:
mcpp-index will declare min_mcpp = 0.0.85 (index.toml floor) and start
using long-bracket descriptors + scan_overrides; pre-0.0.85 binaries
reading those descriptors fail to parse them — upgrade via install.sh.
From 0.0.85 on, the floor mechanism turns every future evolution into a
graceful keep-old-snapshot + upgrade hint instead of a parse error.

Author: Sunrisepeak

docs/05-mcpp-toml.md

@@ -439,6 +439,45 @@ features = {
 }
 ```
 
+### 2.8.3 `[scan_overrides."<glob>"]` — Author-Asserted Scan Results
+
+The default module scanner is a text-level pass that (deliberately) rejects
+`import` statements inside conditional preprocessor blocks. Some legitimate
+module units carry them — e.g. fmt's official `src/fmt.cc` guards
+`import std;` behind `#ifdef FMT_IMPORT_STD`. When the file's import set is
+known and stable, declare it instead of scanning:
+
+```toml
+[modules]
+sources = ["src/**/*.cppm", "vendor/fmt.cc"]
+
+[scan_overrides."vendor/fmt.cc"]
+provides = ["fmt"]      # at most one provided module per unit
+imports  = ["std"]
+```
+
+Files matched by the glob skip the text scan; the declared unit enters the
+module graph directly. The declaration is **audited every build**: the
+compiler's own P1689 scan of the file (the `.ddi` dyndep input) is compared
+against it, and any divergence fails that compile edge with both sides
+printed — a stale declaration cannot silently corrupt the graph. An override
+glob that matches no source file is an error.
+
+The same key exists in xpkg descriptors (index packages):
+
+```lua
+mcpp = {
+    sources  = { "*/src/fmt.cc" },
+    cxxflags = { "-DFMT_IMPORT_STD" },
+    scan_overrides = {
+        ["*/src/fmt.cc"] = { provides = { "fmt" }, imports = { "std" } },
+    },
+}
+```
+
+To extend the plan-vs-ddi audit to *every* module unit (not just overrides),
+set `MCPP_VERIFY_MODGRAPH=1` when generating the build.
+
 ### 2.9 `[profile.<name>]` — Build Profiles
 
 ```toml

mcpp.toml

@@ -1,6 +1,6 @@
 [package]
 name        = "mcpp"
-version     = "0.0.84"
+version     = "0.0.85"
 description = "Modern C++ build & package management tool"
 license     = "Apache-2.0"
 authors     = ["mcpp-community"]

src/toolchain/fingerprint.cppm

@@ -18,7 +18,7 @@ import mcpp.toolchain.detect;
 
 export namespace mcpp::toolchain {
 
-inline constexpr std::string_view MCPP_VERSION = "0.0.84";
+inline constexpr std::string_view MCPP_VERSION = "0.0.85";
 
 struct FingerprintInputs {
     Toolchain                       toolchain;