Refactor YAML operations to use yamlpatch for format preservation

.envrc

@@ -0,0 +1,3 @@
+export CC=gcc
+use guix
+

AGENTS.md

@@ -0,0 +1,8 @@
+Validate your work: `make check`.
+Use Test Driven Development practices. Refactor using Red Green Refactor loops.
+Code MUST be simple, minimal and readable.
+Avoid duplicating code as much as you can.
+Run cargo commands with the `CC=gcc` environment variable.
+When editing YAML, preserve comments and blank lines around untouched keys.
+Touched keys may be replaced with remove/add semantics, even if their comments are lost.
+The tools MUST NEVER reformat a YAML file when editing it.

Cargo.toml

@@ -9,3 +9,7 @@ serde_yaml = "0.9"
 regex = "1"
 serde_json = "1"
 termsize = "0.1"
+yamlpatch = "0.12"
+yamlpath = "0.34"
+subfeature = "0.0.4"
+thiserror = "2"

Makefile

@@ -0,0 +1,16 @@
+.PHONY: check
+
+build:
+    CC=gcc cargo build
+
+test:
+	CC=gcc cargo test
+
+lint:
+	CC=gcc cargo clippy -- -D warnings
+
+check: test lint
+	cargo fmt --check
+	CC=gcc cargo clippy -- -D warnings
+
+.DEFAULT_GOAL := check

README.md

@@ -39,10 +39,10 @@ cargo build --release
     $ ym cp tests/data/config-prod.yaml:database.primary.password tests/data/app-config.yaml:database.secondary.password
 
     $ # Copy value from source.key to destination.key (same file, destination file is optional and defaults to source file)
-    $ ym cp tests/data/app-config.yaml:database.primary.password database.replica.password
+    $ ym cp tests/data/app-config.yaml:database.primary.password :database.replica.password
 
     $ # Copy value to a different file (with same key, destination key is optional and defaults to source key)
-    $ ym cp tests/data/app-config.yaml:app.name tests/data/config-prod.yaml:
+    $ ym cp tests/data/app-config.yaml:app.name tests/data/config-prod.yaml
     ```
 
 - use **mv** to move a value from one key to another (copies then deletes the source):
@@ -52,8 +52,8 @@ cargo build --release
     $ ym mv tests/data/config-prod.yaml:database.primary.password tests/data/app-config.yaml:database.secondary.password
 
     $ # Move value from source.key to destination.key (same file, destination file is optional and defaults to source file)
-    $ ym mv tests/data/app-config.yaml:database.primary.password database.replica.password
+    $ ym mv tests/data/app-config.yaml:database.primary.password :database.replica.password
 
     $ # Move value to a different file (with same key, destination key is optional and defaults to source key)
-    $ ym mv tests/data/app-config.yaml:app.name tests/data/config-prod.yaml:
+    $ ym mv tests/data/app-config.yaml:app.name tests/data/config-prod.yaml
     ```