rmg-core/scheduler: fail-fast drain; u32 radix histogram; keep PendingTx private

.githooks/pre-commit

@@ -1,4 +1,5 @@
 #!/usr/bin/env bash
+# SPDX-License-Identifier: Apache-2.0
 set -euo pipefail
 
 # 1) PRNG coupling guard (existing logic)
@@ -123,4 +124,9 @@ if [[ -n "$DOCS_CHANGED" ]]; then
   fi
 fi
 
+# 8) SPDX header enforcement (code = Apache-2.0; docs/math = Apache-2.0 OR MIND-UCAL-1.0)
+if [[ -x scripts/ensure_spdx.sh ]]; then
+  scripts/ensure_spdx.sh || exit 1
+fi
+
 exit 0

LEGAL.md

@@ -0,0 +1,43 @@
+<!-- SPDX-License-Identifier: Apache-2.0 OR MIND-UCAL-1.0 -->
+
+# Legal Overview
+
+This document explains how licensing works in this repository. It is a summary
+only; if anything here conflicts with the full license texts, those texts
+control (`LICENSE-APACHE`, `LICENSE-MIND-UCAL`).
+
+## 1) Code
+
+- Applies to: Rust source, build scripts, shell/Python/JS tooling, binaries, Makefiles, configs used to build/run the code.
+- License: **Apache License, Version 2.0** only.  
+  See `LICENSE-APACHE`.
+- SPDX for code files: `SPDX-License-Identifier: Apache-2.0`
+
+## 2) Theory / Math / Documentation
+
+- Applies to: `docs/`, `rmg-math/`, LaTeX sources, papers/notes, other written or mathematical materials.
+- License options (your choice):
+  - Apache License, Version 2.0 **OR**
+  - MIND-UCAL License v1.0
+- SPDX for these files: `SPDX-License-Identifier: Apache-2.0 OR MIND-UCAL-1.0`
+- If you do not wish to use MIND-UCAL, you may use all theory, math, and documentation under Apache 2.0 alone. No portion of this repository requires adopting MIND-UCAL.
+
+## 3) SPDX Policy
+
+- All tracked source and documentation files must carry an SPDX header.
+- Enforcement:
+  - `scripts/ensure_spdx.sh` (pre-commit): inserts missing headers into staged files, restages, and aborts so you can review.
+  - `scripts/check_spdx.sh`: check-only helper (unused by default).
+- Patterns:
+  - Code: `Apache-2.0`
+  - Docs/math: `Apache-2.0 OR MIND-UCAL-1.0`
+- Exclusions: generated/binary assets (e.g., target/, node_modules/, PDFs, images) are not labeled.
+
+## 4) NOTICE
+
+See `NOTICE` for attribution. Apache 2.0 requires preservation of NOTICE content in redistributions that include NOTICE.
+
+## 5) No additional terms
+
+No extra terms or conditions beyond the licenses above. Unless required by law,
+all material is provided “AS IS”, without warranties or conditions of any kind.

LICENSE

@@ -1,21 +1,20 @@
-MIT License
+SPDX-License-Identifier: Apache-2.0
+This project is dual-licensed. Different parts of the repository are covered
+by different license options, as follows:
 
-Copyright (c) 2025 Echo Contributors
+1. Code (all source, build scripts, tooling, binaries)
+   - Licensed under the Apache License, Version 2.0 only.
+   - See `LICENSE-APACHE` or https://www.apache.org/licenses/LICENSE-2.0
 
-Permission is hereby granted, free of charge, to any person obtaining a copy
-of this software and associated documentation files (the "Software"), to deal
-in the Software without restriction, including without limitation the rights
-to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-copies of the Software, and to permit persons to whom the Software is
-furnished to do so, subject to the following conditions:
+2. Theory / math / documentation corpus (e.g., `docs/`, `rmg-math/`, papers/notes)
+   - Dual-licensed under:
+       (a) Apache License, Version 2.0, OR
+       (b) MIND-UCAL License v1.0
+   - See `LICENSE-APACHE` and `LICENSE-MIND-UCAL` (canonical text in ../universal-charter/MIND-UCAL/LICENSE).
 
-The above copyright notice and this permission notice shall be included in all
-copies or substantial portions of the Software.
+You may use the theory / math / documentation under EITHER Apache-2.0 OR
+MIND-UCAL v1.0, at your option. If you do not wish to use MIND-UCAL, you may
+use all such materials under Apache-2.0 alone. No portion of this repository
+requires adopting MIND-UCAL.
 
-THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
-SOFTWARE.
+Unless required by applicable law or agreed to in writing, material is provided on an “AS IS” BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND.

LICENSE-APACHE

@@ -0,0 +1,73 @@
+Apache License
+Version 2.0, January 2004
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+
+TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
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+Copyright 2025 Echo Contributors
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+Licensed under the Apache License, Version 2.0 (the "License");
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