PR(DOCS): Add one-off breaking change log

Document the SourceHub-to-Vera and Remote DAC migration in BREAKLOG.md. Explain how intentional one-off breaking changes outside the standing VERSIONING.md exceptions are communicated and add contributor guidance.

Author: shahzadlone

BREAKLOG.md

@@ -0,0 +1,66 @@
+# Breaking Change Log
+
+This log records intentional one-off compatibility breaks that DefraDB ships without waiting for a major release, as described by the [versioning policy](./VERSIONING.md). These are genuine breaking changes, not the standing exceptions in that policy.
+
+Unreleased entries are grouped under their release version when they ship.
+
+## Unreleased
+
+### Rename SourceHub to Vera and SourceHub Document ACP to Remote DAC
+
+The SourceHub project has been renamed to [Vera](https://github.com/sourcenetwork/vera). DefraDB now calls the Vera-backed Document ACP implementation Remote DAC, alongside the existing Local DAC. DefraDB does not retain the former configuration values or API names as compatibility aliases.
+
+DefraDB also adopts Vera's planned `LogID` terminology for the Remote DAC log identifier instead of retaining SourceHub's `ChainID` terminology. The current Vera SDK still accepts this value through `WithChainID`; that implementation detail remains inside the Remote DAC adapter so DefraDB users will not face another rename when Vera updates its API.
+
+Update Remote DAC deployments and integrations to use Vera endpoints and dependencies.
+
+#### Configuration and tooling
+
+| Surface | Previous | Replacement |
+|---------|----------|-------------|
+| Document ACP type | `source-hub` | `remote` |
+| Document ACP type flag | `--document-acp-type source-hub` | `--document-acp-type remote` |
+| Document ACP type environment variable | `DEFRA_ACP_DOCUMENT_TYPE=source-hub` | `DEFRA_ACP_DOCUMENT_TYPE=remote` |
+| Document ACP configuration namespace | `acp.document.sourceHub.*` | `acp.document.remote.*` |
+| Remote DAC log ID configuration | `acp.document.sourceHub.ChainID` | `acp.document.remote.LogID` |
+| Environment-based configuration namespace | `DEFRA_ACP_DOCUMENT_SOURCEHUB_*` | `DEFRA_ACP_DOCUMENT_REMOTE_*` |
+| Remote DAC log ID environment variable | `DEFRA_ACP_DOCUMENT_SOURCEHUB_CHAINID` | `DEFRA_ACP_DOCUMENT_REMOTE_LOGID` |
+| Client address flag | `--source-hub-address` | `--remote-dac-address` |
+| Go module | `github.com/sourcenetwork/sourcehub` | `github.com/sourcenetwork/vera` |
+| Container image | `ghcr.io/sourcenetwork/sourcehub` | `ghcr.io/sourcenetwork/vera` |
+| Integration test ACP type | `DEFRA_DOCUMENT_ACP_TYPE=source-hub` | `DEFRA_DOCUMENT_ACP_TYPE=remote` |
+| Integration test image | `DEFRA_SOURCEHUB_IMAGE` | `DEFRA_VERA_IMAGE` |
+| Make target | `make test:source-hub` | `make test:remote-dac` |
+
+The namespace-only change applies to `GRPCAddress`, `CometRPCAddress`, `KeyName`, and `address`. The `ChainID` setting instead becomes `LogID`, as shown above.
+
+Addresses supplied through `acp.document.remote.address` or `--remote-dac-address`, including the JWT `authorized_account` claim, must use Vera's `vera` Bech32 prefix instead of SourceHub's `source` prefix.
+
+#### Go API
+
+| Previous | Replacement |
+|----------|-------------|
+| `dac.NewSourceHubACP` | `dac.NewRemoteDocumentACP` |
+| `dac.NewACPSourceHub` | `dac.NewRemoteDocumentACPClient` |
+| `dac.NewSourceHubDocumentACP` (JS/WASM) | `dac.NewRemoteDocumentACP` |
+| `dac.SourceHubDocumentACP` | `dac.RemoteDocumentACP` |
+| `SourceHubDocumentACP` in `acp/types` | `RemoteDocumentACP` in `acp/types` |
+| `options.NodeSourceHubDocumentACPType` | `options.NodeRemoteDocumentACPType` |
+| `NodeDocumentACPOptions.SourceHubChainID` | `NodeDocumentACPOptions.RemoteDACLogID` |
+| `NodeDocumentACPOptions.SourceHubGRPCAddress` | `NodeDocumentACPOptions.RemoteDACGRPCAddress` |
+| `NodeDocumentACPOptions.SourceHubCometRPCAddress` | `NodeDocumentACPOptions.RemoteDACCometRPCAddress` |
+| `NodeDocumentACPOptionsBuilder.SetChainID` | `NodeDocumentACPOptionsBuilder.SetLogID` |
+| `node.ErrSignerMissingForSourceHubACP` | `node.ErrSignerMissingForRemoteDAC` |
+| `sourcehub.TxSigner` | `vera.TxSigner` |
+
+#### C API
+
+These mappings are included for migration completeness and do not change the C bindings' [current versioning status](./VERSIONING.md#the-c-embedded-client).
+
+The Document ACP type stored in `NodeInitOptions.documentACPType` changes from `"source-hub"` to `"remote"`. The related fields are renamed as follows:
+
+| Previous | Replacement |
+|----------|-------------|
+| `sourceHubChainID` | `remoteDACLogID` |
+| `sourceHubGRPCAddress` | `remoteDACGRPCAddress` |
+| `sourceHubCometRPCAddress` | `remoteDACCometRPCAddress` |

CONTRIBUTING_INTERNAL.md

@@ -279,7 +279,8 @@ For significant architectural changes or major new features, write a **[Source I
 >
 > 1. Include the `BREAKING CHANGE` keyword in the **commit message body** (not the title)
 > 2. Follow it with a description of what changed and why
-> 3. Document the changes in [`docs/data_format_changes/`](./docs/data_format_changes/) for the change detector to pass
+> 3. For an intentional one-off breaking change outside a major release, add the affected interfaces and migration guidance to [`BREAKLOG.md`](./BREAKLOG.md)
+> 4. If the stored data format changes, document it in [`docs/data_format_changes/`](./docs/data_format_changes/) for the change detector to pass
 
 ---
 

VERSIONING.md

@@ -12,6 +12,12 @@ Generally, we will be incrementing the DefraDB release version in strict accorda
 
 However, in some areas the line is blurry and controversial, and very occasionally deemed to be impractical in the short-term.  The rest of this document outlines these special areas and our versioning policy on them.
 
+## One-off breaking changes
+
+In exceptional cases, we may intentionally ship an isolated breaking change without waiting for a major release. These are genuine compatibility breaks and one-off departures from our usual semantic-versioning policy; they do not establish a new category of unprotected API.
+
+Every such change is recorded in the [breaking change log](./BREAKLOG.md), including the affected interfaces and migration guidance. Consumers should review the entries between their current and target versions before every upgrade.
+
 ## Errors
 
 At the moment, our errors are largely string based - they are driven by a single concrete implementation of the standard Go `error` interface [here](./errors/defraError.go#L60).