diff --git a/crates/pi-natives/src/ast.rs b/crates/pi-natives/src/ast.rs
index 8e74dbc9f..1ecb55c76 100644
--- a/crates/pi-natives/src/ast.rs
+++ b/crates/pi-natives/src/ast.rs
@@ -517,20 +517,13 @@ fn normalize_rewrite_map(
 	rewrites: Option<HashMap<String, String>>,
 ) -> Result<Vec<(String, String)>> {
 	let mut normalized = Vec::new();
-	for (raw_pattern, raw_rewrite) in rewrites.unwrap_or_default() {
-		let pattern = raw_pattern.trim();
+	for (pattern, rewrite) in rewrites.unwrap_or_default() {
 		if pattern.is_empty() {
 			return Err(Error::from_reason(
 				"`rewrites` keys must be non-empty pattern strings".to_string(),
 			));
 		}
-		let rewrite = raw_rewrite.trim();
-		if rewrite.is_empty() {
-			return Err(Error::from_reason(format!(
-				"`rewrites[{pattern}]` must be a non-empty rewrite template"
-			)));
-		}
-		normalized.push((pattern.to_string(), rewrite.to_string()));
+		normalized.push((pattern, rewrite));
 	}
 	if normalized.is_empty() {
 		return Err(Error::from_reason(
diff --git a/packages/coding-agent/CHANGELOG.md b/packages/coding-agent/CHANGELOG.md
index 74649307c..1c3f120b4 100644
--- a/packages/coding-agent/CHANGELOG.md
+++ b/packages/coding-agent/CHANGELOG.md
@@ -20,6 +20,8 @@
 
 ### Fixed
 
+- `ast_replace` no longer rejects empty `out` values; an empty string now deletes matched nodes
+- `ast_replace` no longer trims `pat` and `out` values, preserving intentional whitespace
 - `gemini_image` tool: corrected `responseModalities` values from `'Image'`/`'Text'` to uppercase `'IMAGE'`/`'TEXT'` matching the API enum
 
 ### Breaking Changes
diff --git a/packages/coding-agent/src/tools/ast-replace.ts b/packages/coding-agent/src/tools/ast-replace.ts
index 0e02f9f9a..1e93e4d1d 100644
--- a/packages/coding-agent/src/tools/ast-replace.ts
+++ b/packages/coding-agent/src/tools/ast-replace.ts
@@ -69,15 +69,10 @@ export class AstReplaceTool implements AgentTool<typeof astReplaceSchema, AstRep
 	): Promise<AgentToolResult<AstReplaceToolDetails>> {
 		return untilAborted(signal, async () => {
 			const ops = params.ops.map((entry, index) => {
-				const pat = entry.pat.trim();
-				const out = entry.out.trim();
-				if (pat.length === 0) {
+				if (entry.pat.length === 0) {
 					throw new ToolError(`\`ops[${index}].pat\` must be a non-empty pattern`);
 				}
-				if (out.length === 0) {
-					throw new ToolError(`\`ops[${index}].out\` must be a non-empty replacement template`);
-				}
-				return [pat, out] as const;
+				return [entry.pat, entry.out] as const;
 			});
 			if (ops.length === 0) {
 				throw new ToolError("`ops` must include at least one op entry");
@@ -122,10 +117,7 @@ export class AstReplaceTool implements AgentTool<typeof astReplaceSchema, AstRep
 			}
 
 			const resolvedSearchPath = searchPath ?? resolveToCwd(".", this.session.cwd);
-			const scopePath = (() => {
-				const relative = path.relative(this.session.cwd, resolvedSearchPath).replace(/\\/g, "/");
-				return relative.length === 0 ? "." : relative;
-			})();
+			const scopePath = path.relative(this.session.cwd, resolvedSearchPath).replace(/\\/g, "/") || ".";
 			let isDirectory: boolean;
 			try {
 				const stat = await Bun.file(resolvedSearchPath).stat();