docs(VeraCrypt): add TODO.md and surface the open defect in crossrepostatus

VeraCrypt/README.md

@@ -14,6 +14,7 @@ checked out at [`../VeraCrypt`](../VeraCrypt).
 
 | File | Topic |
 |---|---|
+| [`TODO.md`](TODO.md) | **Start here** — what is open, what is blocked on a decision, what is waiting on upstream |
 | [`upstream-sync.md`](upstream-sync.md) | The fork drifts silently — verify before analysing anything |
 | [`build-verification.md`](build-verification.md) | Building and compile-checking on Linux (Docker) and Windows (native MSVC) |
 | [`coverage-measurement.md`](coverage-measurement.md) | Measuring coverage, why `lcov`/`gcovr` lie here, real figures, and which test attempts paid off |

VeraCrypt/TODO.md

@@ -0,0 +1,92 @@
+# VeraCrypt — open items
+
+Status as of **2026-08-07**, verified against `upstream/master` @ `b48e31f5` (1.26.29).
+
+> **Why this file lives here and not in the repo.** The other tracked repos keep their
+> open work in their own `TODO.md`. VeraCrypt cannot: the fork is used to prepare
+> upstream pull requests, and the findings below are a **local record that must not reach
+> upstream**. A `TODO.md` inside the working copy would sooner or later be swept into a
+> branch. So it stays in the workspace.
+
+## Open — waiting on upstream maintainers
+
+Nothing to do on our side; these are submitted and out of our hands.
+
+| PR | Subject | Since |
+|---|---|---|
+| [#1842](https://github.com/veracrypt/VeraCrypt/pull/1842) | Document that `CRYPTOPP_ALIGN_DATA` can expand to nothing | 2026-08-01 |
+| [#1843](https://github.com/veracrypt/VeraCrypt/pull/1843) | Explicit derived-key alignment in `CreateVolumeHeaderInMemory` | 2026-08-01 |
+| [#1844](https://github.com/veracrypt/VeraCrypt/pull/1844) | Verify `CRYPTOPP_ALIGN_DATA` delivers the requested alignment | 2026-08-01 |
+| [#1850](https://github.com/veracrypt/VeraCrypt/pull/1850) | 14 test blocks covering the crypto and platform layers | 2026-08-07 |
+
+**Merge order matters:** #1850 asks for **#1844 to land first** — both touch
+`src/Volume/EncryptionTest.{cpp,h}` at different points. `git apply` fails, `git apply -3`
+succeeds. The note is already in the #1850 description; no follow-up needed unless a
+maintainer merges them the other way round.
+
+## Open — decided against reporting, fix designed but not applied
+
+### 1. Check-then-lock race in `RandomNumberGenerator` — the one real defect
+
+Reproduced on unmodified source; a two-thread driver segfaults. Full analysis, the
+standalone reproducer and the three-step fix are in
+[`concurrency-findings.md`](concurrency-findings.md#suggested-fix).
+
+Fix in short — smallest step first:
+
+1. move the `Running` guard **inside** `ScopeLock` in `AddToPool` and `GetData`
+2. make `Running` a `std::atomic<bool>` (`volatile` does not help)
+3. join the creation thread — this is the root cause; 1 and 2 only make it unreachable
+
+**Blocked by a decision, not by missing knowledge.** Deliberately not reported upstream.
+Applying it would mean opening a production-code PR, which is out of scope for now.
+
+**If it is ever picked up:** verify with the reproducer (unpatched segfaults, patched must
+print `survived N rounds`) *and* re-run `veracrypt --test` — `TestRandomNumberGenerator`
+catches a "fix" that deletes the guard instead of moving it.
+
+### 2. `VolumeCreator` thread is neither joined nor detached
+
+`Core/VolumeCreator.cpp:436` — the only `Thread::Start` in the tree with no matching
+`Join()` or `Detach()`. `Abort()` only sets a flag, `~VolumeCreator` is empty. This is what
+makes item 1 constructible. Same decision applies.
+
+## Open — robustness, no live defect
+
+| Item | Where | Status |
+|---|---|---|
+| `VolumeLayout` dereferences `Header` unguarded | `Volume/VolumeLayout.cpp:131, 136, 180, 185` | Not reachable in production (`Volume.cpp:197` sets the header first). Inconsistent with the `NotInitialized` style used elsewhere. |
+| `EncryptionMode::ValidateParameters` has no callers | `Volume/EncryptionMode.cpp:59, 65` | Production never validates these parameters. Coverage stuck at 38.71 % and **cannot be raised honestly** — calling it from a test would paint the line green and hide the point. |
+| `ValidateState()` compiled out of Release | 13 sites, all `if_debug(...)` | Presumably deliberate. Do not treat as a safety net; do not write tests for it. |
+
+## Open — coverage gaps that need fixtures
+
+Both were predicted before writing anything and are not reachable without new
+infrastructure:
+
+- **`Volume/Keyfile.cpp` stops at 47 %** — the security-token and directory-enumeration
+  branches need a PKCS#11 token or a populated directory.
+- **`Volume/VolumeHeader.cpp` barely moves (82 %)** — the remaining part is the
+  decrypt-attempt loop, which needs a real encrypted volume.
+
+A fixture volume created once and checked in would unlock both, at the cost of a binary
+test asset. Not attempted.
+
+## Known weakness in the tests we submitted
+
+Recorded so it is not rediscovered as a surprise — details in
+[`test-coverage-work.md`](test-coverage-work.md#weaknesses-that-remain):
+
+- Breaking the `Running` check in `AddToPool` goes **undetected** by the suite. It is
+  covered by line coverage but asserted by nothing. Coverage is not detection.
+- `TestVolumeHeaderRejection` relies on `catch (PasswordEmpty&)`; a change of exception
+  type still fails the suite, but the attribution becomes unclear.
+
+## Done
+
+- Fork brought up to date — it had drifted 16 months (394 commits). See
+  [`upstream-sync.md`](upstream-sync.md); **check this before analysing anything.**
+- Coverage measurement method established, including why `lcov`/`gcovr` report wrong
+  numbers here — [`coverage-measurement.md`](coverage-measurement.md).
+- 14 test blocks written, each verified by injecting a defect — 16 of 17 injected defects
+  attributed to the new test itself.

crossrepostatus.md

@@ -12,6 +12,8 @@ Single-repo open work lives in each repo's own `TODO.md`:
 - [`../java-llama.cpp/TODO.md`](../java-llama.cpp/TODO.md)
 - [`../srcmorph/TODO.md`](../srcmorph/TODO.md)
 - [`../streambuffer/TODO.md`](../streambuffer/TODO.md)
+- [`VeraCrypt/TODO.md`](VeraCrypt/TODO.md) — **kept here, not in the repo**: the fork is used to
+  prepare upstream PRs, and these items are a local record that must not reach upstream.
 
 Recurring per-repo audits (mostly cross-repo by nature but living per-repo today) are documented in [`policies/code-quality-todos.md`](policies/code-quality-todos.md).
 
@@ -23,7 +25,8 @@ Repos — **Java tier** (shared Maven/JUnit toolchain, governed by the guides an
 
 **Other tracked repos** — no shared Java toolchain, each with its own conventions and its own
 knowledge folder here:
-- **VeraCrypt** (C/C++) = `/home/user/VeraCrypt` — see [`VeraCrypt/`](VeraCrypt/): build and coverage tooling, submitted PRs, local-only findings
+- **VeraCrypt** (C/C++) = `/home/user/VeraCrypt` — see [`VeraCrypt/`](VeraCrypt/): build and coverage tooling, submitted PRs, local-only findings.
+  Status: 4 PRs pending upstream, and **one reproduced defect (RNG check-then-lock race) that is deliberately unfixed and unreported** — fix designed, see [`VeraCrypt/TODO.md`](VeraCrypt/TODO.md)
 - **llama.cpp** (C/C++) = `/home/user/llama.cpp` — see [`llama.cpp/`](llama.cpp/)
 - **subprocess.h** (C) = `/home/user/subprocess.h` — see [`subprocess.h/`](subprocess.h/)