feat: introduce PreBlock (#17421)

docs/architecture/README.md

@@ -93,3 +93,4 @@ When writing ADRs, follow the same best practices for writing RFCs. When writing
 * [ADR 044: Guidelines for Updating Protobuf Definitions](./adr-044-protobuf-updates-guidelines.md)
 * [ADR 047: Extend Upgrade Plan](./adr-047-extend-upgrade-plan.md)
 * [ADR 053: Go Module Refactoring](./adr-053-go-module-refactoring.md)
+* [ADR 068: Preblock](./adr-068-preblock.md)

docs/architecture/adr-063-core-module-api.md

@@ -280,6 +280,17 @@ type HasGenesis interface {
 }
 ```
 
+#### Pre Blockers
+
+Modules that have functionality that runs before BeginBlock and should implement the has `HasPreBlocker` interfaces:
+
+```go
+type HasPreBlocker interface {
+  AppModule
+  PreBlock(context.Context) error
+}
+```
+
 #### Begin and End Blockers
 
 Modules that have functionality that runs before transactions (begin blockers) or after transactions

docs/architecture/adr-068-preblock.md

@@ -0,0 +1,60 @@
+# ADR 068: Preblock
+
+## Changelog
+
+* Sept 13, 2023: Initial Draft
+
+## Status
+
+DRAFT
+
+## Abstract
+
+Introduce `PreBlock`, which runs before begin blocker other modules, and allows to modify consensus parameters, and the changes are visible to the following state machine logics.
+
+## Context
+
+When upgrading to sdk 0.47, the storage format for consensus parameters changed, but in the migration block, `ctx.ConsensusParams()` is always `nil`, because it fails to load the old format using new code, it's supposed to be migrated by the `x/upgrade` module first, but unfortunately, the migration happens in `BeginBlocker` handler, which runs after the `ctx` is initialized.
+When we try to solve this, we find the `x/upgrade` module can't modify the context to make the consensus parameters visible for the other modules, the context is passed by value, and sdk team want to keep it that way, that's good for isolations between modules.
+
+## Alternatives
+
+The first alternative solution introduced a `MigrateModuleManager`, which only includes the `x/upgrade` module right now, and baseapp will run their `BeginBlocker`s before the other modules, and reload context's consensus parameters in between.
+
+## Decision
+
+Suggested this new lifecycle method.
+
+### `PreBlocker`
+
+There are two semantics around the new lifecycle method:
+
+- It runs before the `BeginBlocker` of all modules
+- It can modify consensus parameters in storage, and signal the caller through the return value.
+
+When it returns `ConsensusParamsChanged=true`, the caller must refresh the consensus parameter in the finalize context:
+```
+app.finalizeBlockState.ctx = app.finalizeBlockState.ctx.WithConsensusParams(app.GetConsensusParams())
+```
+
+The new ctx must be passed to all the other lifecycle methods.
+
+
+## Consequences
+
+### Backwards Compatibility
+
+### Positive
+
+### Negative
+
+### Neutral
+
+## Further Discussions
+
+## Test Cases
+
+## References
+* [1] https://github.com/cosmos/cosmos-sdk/issues/16494
+* [2] https://github.com/cosmos/cosmos-sdk/pull/16583
+* [3] https://github.com/cosmos/cosmos-sdk/pull/17421