Establish canonical developer documentation structure

docs/internal/adapters.md

@@ -145,6 +145,37 @@ Adapters do not add durable run state.
 - `internal/format/prepared_run_test.go`
 - `internal/llm/openai_compatible_client_test.go`
 
+## Change Recipes
+
+### Application Configuration Fields
+
+1. Add the field to the relevant `internal/config` shape and default handling.
+2. Parse and validate it, then preserve configuration and CLI-override
+   precedence while wiring it through its consuming adapter.
+3. Add focused configuration and adapter tests for parsing, mapping, and
+   effective behavior.
+4. Update the [configuration contract](../config.md) and any external contract
+   affected by the new behavior.
+
+### CLI Flags
+
+1. Add the flag to the relevant command in `internal/adapter/cli/run.go`.
+2. Keep command scope and application-configuration precedence intentional.
+3. Add or update parser and command tests in
+   `internal/adapter/cli/run_test.go`.
+4. Update the [CLI contract](../cli.md) and any maintained examples affected by
+   the invocation.
+
+### Adapter Capabilities
+
+1. Define or reuse the appropriate domain or use-case interface boundary.
+2. Implement translation and IO behavior in the adapter without moving
+   use-case decisions out of `internal/usecase`.
+3. Add focused mapping, parsing, and error-behavior tests.
+4. Update this document and the affected canonical public or integration
+   contract. Update [source internals](sources.md) when source-loading behavior
+   changes.
+
 ## Architectural Invariants
 
 - Adapter packages stay thin and translation-focused.