source adapter framework

docs/command-cheatsheet.md

@@ -41,6 +41,14 @@ mkt ref resolve context.md 'std:clauses.md#payment-terms' --root examples/refere
 mkt process file.md --root .
 ```
 
+## Normalize External Sources
+
+```bash
+mkt source adapters
+mkt source inspect book.epub --adapter source.epub3 --format json
+mkt source normalize book.epub --adapter source.epub3 --format markdown --output book.md
+```
+
 ## Split And Literate Workflows
 
 ```bash
@@ -102,6 +110,7 @@ mkt context list
 mkt completion bash --instructions
 mkt extension list
 mkt extension inspect backend.local-sqlite
+mkt extension inspect source.adapter-registry
 mkt extension commands
 mkt docs cli --output docs/cli-reference.md
 mkt docs api --output docs/api-reference.md