Initial repo creation for CAC3 (Californiacoin3).

Placeholder docs only — no source code yet.
Renaming and fresh genesis block coming in subsequent commits.

.gitignore

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+# Build artifacts
+*.o
+*.a
+*.so
+*.dylib
+*.dll
+
+# CAC3 / Bitcoin Core build outputs
+src/cac3d
+src/cac3-cli
+src/cac3-tx
+src/cac3-wallet
+src/cac3-qt
+src/qt/cac3-qt
+src/test/test_cac3
+src/bench/bench_cac3
+*.exe
+
+# Generated build tree
+depends/built/
+depends/sdk-sources/
+src/config/cac3-config.h
+src/leveldb/libleveldb.a
+src/secp256k1/libsecp256k1.a
+
+# Autotools
+*.in~
+config.status
+config.log
+Makefile
+src/Makefile
+src/test/Makefile
+src/qt/Makefile
+doc/Doxyfile
+!configure.ac
+!Makefile.am
+
+# ctags / IDE
+.tags
+.idea/
+.vscode/
+*.swp
+
+# OS
+.DS_Store
+Thumbs.db

CAC3-LAUNCH.md

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+# CAC3 Launch Plan — Pending
+
+## What needs to happen before the first block
+
+1. Bring over the Bitcoin Core 0.18 source tree from
+   [SamiAhmed7777/nyc3](https://github.com/SamiAhmed7777/nyc3) (or the
+   barrystyle/nyc3 upstream it was forked from).
+2. Rename pass on every string literal:
+   - `nyc3` → `cac3`
+   - `NYC3` → `CAC3`
+   - `NewYorkCoin` → `Californiacoin`
+   - port `55555` → `55556`
+   - magic bytes `1f be ef f1` → fresh values
+   - P2PKH base58 prefix `0x35` → `0x1e` (Bitcoin's `'C'` letter)
+   - bech32 HRP `ny` → `cac`
+3. Mine a fresh genesis block (find new nonce, recompute merkle root).
+4. Replace genesis constants in `src/chainparams.cpp` and
+   `src/chainparamsbase.cpp`.
+5. Replace seed nodes with CAC3-run infrastructure.
+6. Build `cac3d` + `cac3-cli`. Drop Qt wallet unless a maintainer
+   volunteers for the GUI.
+7. Run 3+ full nodes on hard, geographic diversity.
+8. Mine the first 150 blocks (no difficulty adjustment until height 151).
+9. Open the network — clients can connect.
+
+## What is NOT changing
+- Argon2s PoW parameters — preserved exactly
+- LWMA-3 difficulty algorithm — preserved exactly
+- 10-second block target — preserved exactly
+- Total supply schedule — preserved exactly
+- Address format (bech32 + base58 P2PKH + P2SH) — preserved exactly
+
+## What this repo intentionally does NOT carry
+The trust history of any prior chain. CAC3 starts at height 0 with
+fresh state. There is no on-chain bridge from any prior identity.

README.md

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+# CAC3 (Californiacoin3) — integration/staging tree
+
+## What this is
+A fork of Bitcoin Core 0.18 with a CPU-mineable proof-of-work (Argon2s),
+a difficulty-adjustment algorithm tuned for fast block spacing (LWMA-3),
+and 10-second block times — explicitly designed to keep mining fair to
+anyone with general-purpose hardware.
+
+The full body of work is being brought over from
+[SamiAhmed7777/nyc3](https://github.com/SamiAhmed7777/nyc3), the previous
+identity this codebase ran under, with the consensus algorithm and
+parameters held constant — only the chain identity (genesis, magic bytes,
+ports, address prefixes, ticker) is changing.
+
+## Status
+Initial repo creation. No source has been pushed yet. The rename and
+fresh genesis block are pending a deliberate launch step.
+
+## License
+MIT — see COPYING once the upstream Bitcoin Core license stub lands.
+
+## Acknowledgement
+The Argon2s implementation, the LWMA-3 difficulty algorithm, and the
+base Bitcoin Core 0.18 fork that this project stands on come from the
+open-source ecosystem around [barrystyle](https://github.com/barrystyle),
+[barrystyle/argon2s](https://github.com/barrystyle/argon2s), and
+[barrystyle/nyc3](https://github.com/barrystyle/nyc3). This fork honours
+their work.