diff --git a/docs/genaisrc/genaiscript.d.ts b/docs/genaisrc/genaiscript.d.ts
index f9f02e4454..5e88b248f2 100644
--- a/docs/genaisrc/genaiscript.d.ts
+++ b/docs/genaisrc/genaiscript.d.ts
@@ -1908,7 +1908,7 @@ interface ChatGenerationContext extends ChatTurnGenerationContext {
         options?: ChatParticipantOptions
     ): void
     defFileOutput(
-        pattern: string | string[],
+        pattern: ElementOrArray<string | WorkspaceFile>,
         description?: string,
         options?: FileOutputOptions
     ): void
@@ -2791,7 +2791,7 @@ declare function def(
  * @param options expectations about the generated file content
  */
 declare function defFileOutput(
-    pattern: string | string[],
+    pattern: ElementOrArray<string | WorkspaceFile>,
     description?: string,
     options?: FileOutputOptions
 ): void
diff --git a/docs/src/content/docs/reference/cli/commands.md b/docs/src/content/docs/reference/cli/commands.md
index 0497de539b..3d778fa2b5 100644
--- a/docs/src/content/docs/reference/cli/commands.md
+++ b/docs/src/content/docs/reference/cli/commands.md
@@ -18,7 +18,6 @@ Runs a GenAIScript against files.
 Options:
   -ef, --excluded-files <string...>          excluded files
   -egi, --exclude-git-ignore                 exclude files that are ignored through the .gitignore file in the workspace root
-  -fcs, --file-chunk-size <number>           file chunk size
   -o, --out <string>                         output folder. Extra markdown fields for output and trace will also be generated
   -rmo, --remove-out                         remove output folder if it exists
   -ot, --out-trace <string>                  output file for trace
@@ -236,9 +235,9 @@ Options:
 
 ## `retrieval`
 
-```
 Usage: genaiscript retrieval|retreival [options] [command]
 
+RAG support
 RAG support
 
 Options:
diff --git a/docs/src/content/docs/samples/gai.mdx b/docs/src/content/docs/samples/gai.mdx
index 18f0a269d4..f4c93a236a 100644
--- a/docs/src/content/docs/samples/gai.mdx
+++ b/docs/src/content/docs/samples/gai.mdx
@@ -2,7 +2,16 @@
 title: GitHub Action Investigator
 description: Investigate GitHub Actions failures
 sidebar:
-    order: 20
+    order: 100
 ---
+import { Code } from "@astrojs/starlight/components"
+import source from "../../../../../packages/sample/genaisrc/gai.genai.mts?raw"
+import gasource from "../../../../../.github/workflows/genai-investigator.yml?raw"
 
 This is an in-depth guide to build a script that interactively investigates GitHub Actions failures.
+
+## Full source ([GitHub](https://github.com/microsoft/genaiscript/blob/main/packages/sample/genaisrc/gai.genai.mts))
+
+<Code code={source} wrap={true} lang="ts" title="gai.genai.mts" />
+
+<Code code={gasource} wrap={true} lang="yaml" title="gai.yml" />
diff --git a/docs/src/content/docs/samples/sc.mdx b/docs/src/content/docs/samples/sc.mdx
new file mode 100644
index 0000000000..07ba6a2994
--- /dev/null
+++ b/docs/src/content/docs/samples/sc.mdx
@@ -0,0 +1,13 @@
+---
+title: Spell Check
+description: Spell check a document
+sidebar:
+    order: 101
+---
+
+import { Code } from "@astrojs/starlight/components"
+import source from "../../../../../packages/sample/genaisrc/sc.genai.mts?raw"
+
+## Full source ([GitHub](https://github.com/microsoft/genaiscript/blob/main/packages/sample/genaisrc/sc.genai.mts))
+
+<Code code={source} wrap={true} lang="ts" title="sc.genai.mts" />
diff --git a/genaisrc/genaiscript.d.ts b/genaisrc/genaiscript.d.ts
index f9f02e4454..5e88b248f2 100644
--- a/genaisrc/genaiscript.d.ts
+++ b/genaisrc/genaiscript.d.ts
@@ -1908,7 +1908,7 @@ interface ChatGenerationContext extends ChatTurnGenerationContext {
         options?: ChatParticipantOptions
     ): void
     defFileOutput(
-        pattern: string | string[],
+        pattern: ElementOrArray<string | WorkspaceFile>,
         description?: string,
         options?: FileOutputOptions
     ): void
@@ -2791,7 +2791,7 @@ declare function def(
  * @param options expectations about the generated file content
  */
 declare function defFileOutput(
-    pattern: string | string[],
+    pattern: ElementOrArray<string | WorkspaceFile>,
     description?: string,
     options?: FileOutputOptions
 ): void
diff --git a/packages/auto/genaiscript.d.ts b/packages/auto/genaiscript.d.ts
index f9f02e4454..5e88b248f2 100644
--- a/packages/auto/genaiscript.d.ts
+++ b/packages/auto/genaiscript.d.ts
@@ -1908,7 +1908,7 @@ interface ChatGenerationContext extends ChatTurnGenerationContext {
         options?: ChatParticipantOptions
     ): void
     defFileOutput(
-        pattern: string | string[],
+        pattern: ElementOrArray<string | WorkspaceFile>,
         description?: string,
         options?: FileOutputOptions
     ): void
@@ -2791,7 +2791,7 @@ declare function def(
  * @param options expectations about the generated file content
  */
 declare function defFileOutput(
-    pattern: string | string[],
+    pattern: ElementOrArray<string | WorkspaceFile>,
     description?: string,
     options?: FileOutputOptions
 ): void
diff --git a/packages/core/src/genaisrc/genaiscript.d.ts b/packages/core/src/genaisrc/genaiscript.d.ts
index f9f02e4454..5e88b248f2 100644
--- a/packages/core/src/genaisrc/genaiscript.d.ts
+++ b/packages/core/src/genaisrc/genaiscript.d.ts
@@ -1908,7 +1908,7 @@ interface ChatGenerationContext extends ChatTurnGenerationContext {
         options?: ChatParticipantOptions
     ): void
     defFileOutput(
-        pattern: string | string[],
+        pattern: ElementOrArray<string | WorkspaceFile>,
         description?: string,
         options?: FileOutputOptions
     ): void
@@ -2791,7 +2791,7 @@ declare function def(
  * @param options expectations about the generated file content
  */
 declare function defFileOutput(
-    pattern: string | string[],
+    pattern: ElementOrArray<string | WorkspaceFile>,
     description?: string,
     options?: FileOutputOptions
 ): void
diff --git a/packages/core/src/runpromptcontext.ts b/packages/core/src/runpromptcontext.ts
index 39929596cb..33592f4c1e 100644
--- a/packages/core/src/runpromptcontext.ts
+++ b/packages/core/src/runpromptcontext.ts
@@ -318,7 +318,7 @@ export function createChatGenerationContext(
     }
 
     const defFileOutput = (
-        pattern: string,
+        pattern: ElementOrArray<string | WorkspaceFile>,
         description: string,
         options?: FileOutputOptions
     ): void => {
@@ -326,7 +326,9 @@ export function createChatGenerationContext(
             appendChild(
                 node,
                 createFileOutput({
-                    pattern: arrayify(pattern),
+                    pattern: arrayify(pattern).map((p) =>
+                        typeof p === "string" ? p : p.filename
+                    ),
                     description,
                     options,
                 })
diff --git a/packages/core/src/types/prompt_template.d.ts b/packages/core/src/types/prompt_template.d.ts
index 5bf54dd708..f86b5649cb 100644
--- a/packages/core/src/types/prompt_template.d.ts
+++ b/packages/core/src/types/prompt_template.d.ts
@@ -1875,7 +1875,7 @@ interface ChatGenerationContext extends ChatTurnGenerationContext {
         options?: ChatParticipantOptions
     ): void
     defFileOutput(
-        pattern: string | string[],
+        pattern: ElementOrArray<string | WorkspaceFile>,
         description?: string,
         options?: FileOutputOptions
     ): void
diff --git a/packages/core/src/types/prompt_type.d.ts b/packages/core/src/types/prompt_type.d.ts
index e68f36323d..fa5cfd7e77 100644
--- a/packages/core/src/types/prompt_type.d.ts
+++ b/packages/core/src/types/prompt_type.d.ts
@@ -83,7 +83,7 @@ declare function def(
  * @param options expectations about the generated file content
  */
 declare function defFileOutput(
-    pattern: string | string[],
+    pattern: ElementOrArray<string | WorkspaceFile>,
     description?: string,
     options?: FileOutputOptions
 ): void
diff --git a/packages/sample/genaisrc/blog/genaiscript.d.ts b/packages/sample/genaisrc/blog/genaiscript.d.ts
index f9f02e4454..5e88b248f2 100644
--- a/packages/sample/genaisrc/blog/genaiscript.d.ts
+++ b/packages/sample/genaisrc/blog/genaiscript.d.ts
@@ -1908,7 +1908,7 @@ interface ChatGenerationContext extends ChatTurnGenerationContext {
         options?: ChatParticipantOptions
     ): void
     defFileOutput(
-        pattern: string | string[],
+        pattern: ElementOrArray<string | WorkspaceFile>,
         description?: string,
         options?: FileOutputOptions
     ): void
@@ -2791,7 +2791,7 @@ declare function def(
  * @param options expectations about the generated file content
  */
 declare function defFileOutput(
-    pattern: string | string[],
+    pattern: ElementOrArray<string | WorkspaceFile>,
     description?: string,
     options?: FileOutputOptions
 ): void
diff --git a/packages/sample/genaisrc/genaiscript.d.ts b/packages/sample/genaisrc/genaiscript.d.ts
index f9f02e4454..5e88b248f2 100644
--- a/packages/sample/genaisrc/genaiscript.d.ts
+++ b/packages/sample/genaisrc/genaiscript.d.ts
@@ -1908,7 +1908,7 @@ interface ChatGenerationContext extends ChatTurnGenerationContext {
         options?: ChatParticipantOptions
     ): void
     defFileOutput(
-        pattern: string | string[],
+        pattern: ElementOrArray<string | WorkspaceFile>,
         description?: string,
         options?: FileOutputOptions
     ): void
@@ -2791,7 +2791,7 @@ declare function def(
  * @param options expectations about the generated file content
  */
 declare function defFileOutput(
-    pattern: string | string[],
+    pattern: ElementOrArray<string | WorkspaceFile>,
     description?: string,
     options?: FileOutputOptions
 ): void
diff --git a/packages/sample/genaisrc/node/genaiscript.d.ts b/packages/sample/genaisrc/node/genaiscript.d.ts
index f9f02e4454..5e88b248f2 100644
--- a/packages/sample/genaisrc/node/genaiscript.d.ts
+++ b/packages/sample/genaisrc/node/genaiscript.d.ts
@@ -1908,7 +1908,7 @@ interface ChatGenerationContext extends ChatTurnGenerationContext {
         options?: ChatParticipantOptions
     ): void
     defFileOutput(
-        pattern: string | string[],
+        pattern: ElementOrArray<string | WorkspaceFile>,
         description?: string,
         options?: FileOutputOptions
     ): void
@@ -2791,7 +2791,7 @@ declare function def(
  * @param options expectations about the generated file content
  */
 declare function defFileOutput(
-    pattern: string | string[],
+    pattern: ElementOrArray<string | WorkspaceFile>,
     description?: string,
     options?: FileOutputOptions
 ): void
diff --git a/packages/sample/genaisrc/python/genaiscript.d.ts b/packages/sample/genaisrc/python/genaiscript.d.ts
index f9f02e4454..5e88b248f2 100644
--- a/packages/sample/genaisrc/python/genaiscript.d.ts
+++ b/packages/sample/genaisrc/python/genaiscript.d.ts
@@ -1908,7 +1908,7 @@ interface ChatGenerationContext extends ChatTurnGenerationContext {
         options?: ChatParticipantOptions
     ): void
     defFileOutput(
-        pattern: string | string[],
+        pattern: ElementOrArray<string | WorkspaceFile>,
         description?: string,
         options?: FileOutputOptions
     ): void
@@ -2791,7 +2791,7 @@ declare function def(
  * @param options expectations about the generated file content
  */
 declare function defFileOutput(
-    pattern: string | string[],
+    pattern: ElementOrArray<string | WorkspaceFile>,
     description?: string,
     options?: FileOutputOptions
 ): void
diff --git a/packages/sample/genaisrc/sc.genai.mts b/packages/sample/genaisrc/sc.genai.mts
index 2e3ad27036..8e33b914d0 100644
--- a/packages/sample/genaisrc/sc.genai.mts
+++ b/packages/sample/genaisrc/sc.genai.mts
@@ -1,14 +1,34 @@
 script({
     title: "Spell checker",
-    system: ["system", "system.files"],
+    system: ["system", "system.files", "system.diff"],
+    temperature: 0.1,
 })
 
-const files = def("FILES", env.files, { endsWith: [".md", ".mdx"] })
+// Get files from environment or modified files from Git if none provided
+let files = env.files
+if (files.length === 0) {
+    // If no files are provided, read all modified files
+    const gitStatus = await host.exec("git status --porcelain")
+    const rx = /^\s+[M|U]\s+/ // modified or untracked
+    files = await Promise.all(
+        gitStatus.stdout
+            .split(/\r?\n/g)
+            .filter((filename) => rx.test(filename))
+            .filter((filename) => /\.(md|mdx)$/.test(filename))
+            .map(
+                async (filename) =>
+                    await workspace.readText(filename.replace(rx, ""))
+            )
+    )
+}
+def("FILES", files, { endsWith: [".md", ".mdx"] })
 
-$`Fix the spelling and gramme of the content of ${files}.
+$`Fix the spelling and gramme of the content of FILES. Use diff format for small changes.
 
 - do NOT fix the frontmatter
 - do NOT fix code regions
 - do NOT fix \`code\` and \`\`\`code\`\`\`
 - in .mdx files, do NOT fix inline typescript code
 `
+
+defFileOutput(files, "fixed markdown or mdx files")
diff --git a/packages/sample/genaisrc/style/genaiscript.d.ts b/packages/sample/genaisrc/style/genaiscript.d.ts
index f9f02e4454..5e88b248f2 100644
--- a/packages/sample/genaisrc/style/genaiscript.d.ts
+++ b/packages/sample/genaisrc/style/genaiscript.d.ts
@@ -1908,7 +1908,7 @@ interface ChatGenerationContext extends ChatTurnGenerationContext {
         options?: ChatParticipantOptions
     ): void
     defFileOutput(
-        pattern: string | string[],
+        pattern: ElementOrArray<string | WorkspaceFile>,
         description?: string,
         options?: FileOutputOptions
     ): void
@@ -2791,7 +2791,7 @@ declare function def(
  * @param options expectations about the generated file content
  */
 declare function defFileOutput(
-    pattern: string | string[],
+    pattern: ElementOrArray<string | WorkspaceFile>,
     description?: string,
     options?: FileOutputOptions
 ): void
diff --git a/packages/sample/src/aici/genaiscript.d.ts b/packages/sample/src/aici/genaiscript.d.ts
index f9f02e4454..5e88b248f2 100644
--- a/packages/sample/src/aici/genaiscript.d.ts
+++ b/packages/sample/src/aici/genaiscript.d.ts
@@ -1908,7 +1908,7 @@ interface ChatGenerationContext extends ChatTurnGenerationContext {
         options?: ChatParticipantOptions
     ): void
     defFileOutput(
-        pattern: string | string[],
+        pattern: ElementOrArray<string | WorkspaceFile>,
         description?: string,
         options?: FileOutputOptions
     ): void
@@ -2791,7 +2791,7 @@ declare function def(
  * @param options expectations about the generated file content
  */
 declare function defFileOutput(
-    pattern: string | string[],
+    pattern: ElementOrArray<string | WorkspaceFile>,
     description?: string,
     options?: FileOutputOptions
 ): void
diff --git a/packages/sample/src/errors/genaiscript.d.ts b/packages/sample/src/errors/genaiscript.d.ts
index f9f02e4454..5e88b248f2 100644
--- a/packages/sample/src/errors/genaiscript.d.ts
+++ b/packages/sample/src/errors/genaiscript.d.ts
@@ -1908,7 +1908,7 @@ interface ChatGenerationContext extends ChatTurnGenerationContext {
         options?: ChatParticipantOptions
     ): void
     defFileOutput(
-        pattern: string | string[],
+        pattern: ElementOrArray<string | WorkspaceFile>,
         description?: string,
         options?: FileOutputOptions
     ): void
@@ -2791,7 +2791,7 @@ declare function def(
  * @param options expectations about the generated file content
  */
 declare function defFileOutput(
-    pattern: string | string[],
+    pattern: ElementOrArray<string | WorkspaceFile>,
     description?: string,
     options?: FileOutputOptions
 ): void
diff --git a/packages/sample/src/genaiscript.d.ts b/packages/sample/src/genaiscript.d.ts
index f9f02e4454..5e88b248f2 100644
--- a/packages/sample/src/genaiscript.d.ts
+++ b/packages/sample/src/genaiscript.d.ts
@@ -1908,7 +1908,7 @@ interface ChatGenerationContext extends ChatTurnGenerationContext {
         options?: ChatParticipantOptions
     ): void
     defFileOutput(
-        pattern: string | string[],
+        pattern: ElementOrArray<string | WorkspaceFile>,
         description?: string,
         options?: FileOutputOptions
     ): void
@@ -2791,7 +2791,7 @@ declare function def(
  * @param options expectations about the generated file content
  */
 declare function defFileOutput(
-    pattern: string | string[],
+    pattern: ElementOrArray<string | WorkspaceFile>,
     description?: string,
     options?: FileOutputOptions
 ): void
diff --git a/packages/sample/src/makecode/genaiscript.d.ts b/packages/sample/src/makecode/genaiscript.d.ts
index f9f02e4454..5e88b248f2 100644
--- a/packages/sample/src/makecode/genaiscript.d.ts
+++ b/packages/sample/src/makecode/genaiscript.d.ts
@@ -1908,7 +1908,7 @@ interface ChatGenerationContext extends ChatTurnGenerationContext {
         options?: ChatParticipantOptions
     ): void
     defFileOutput(
-        pattern: string | string[],
+        pattern: ElementOrArray<string | WorkspaceFile>,
         description?: string,
         options?: FileOutputOptions
     ): void
@@ -2791,7 +2791,7 @@ declare function def(
  * @param options expectations about the generated file content
  */
 declare function defFileOutput(
-    pattern: string | string[],
+    pattern: ElementOrArray<string | WorkspaceFile>,
     description?: string,
     options?: FileOutputOptions
 ): void
diff --git a/packages/sample/src/tla/genaiscript.d.ts b/packages/sample/src/tla/genaiscript.d.ts
index f9f02e4454..5e88b248f2 100644
--- a/packages/sample/src/tla/genaiscript.d.ts
+++ b/packages/sample/src/tla/genaiscript.d.ts
@@ -1908,7 +1908,7 @@ interface ChatGenerationContext extends ChatTurnGenerationContext {
         options?: ChatParticipantOptions
     ): void
     defFileOutput(
-        pattern: string | string[],
+        pattern: ElementOrArray<string | WorkspaceFile>,
         description?: string,
         options?: FileOutputOptions
     ): void
@@ -2791,7 +2791,7 @@ declare function def(
  * @param options expectations about the generated file content
  */
 declare function defFileOutput(
-    pattern: string | string[],
+    pattern: ElementOrArray<string | WorkspaceFile>,
     description?: string,
     options?: FileOutputOptions
 ): void
diff --git a/packages/sample/src/vision/genaiscript.d.ts b/packages/sample/src/vision/genaiscript.d.ts
index f9f02e4454..5e88b248f2 100644
--- a/packages/sample/src/vision/genaiscript.d.ts
+++ b/packages/sample/src/vision/genaiscript.d.ts
@@ -1908,7 +1908,7 @@ interface ChatGenerationContext extends ChatTurnGenerationContext {
         options?: ChatParticipantOptions
     ): void
     defFileOutput(
-        pattern: string | string[],
+        pattern: ElementOrArray<string | WorkspaceFile>,
         description?: string,
         options?: FileOutputOptions
     ): void
@@ -2791,7 +2791,7 @@ declare function def(
  * @param options expectations about the generated file content
  */
 declare function defFileOutput(
-    pattern: string | string[],
+    pattern: ElementOrArray<string | WorkspaceFile>,
     description?: string,
     options?: FileOutputOptions
 ): void
diff --git a/packages/vscode/genaisrc/genaiscript.d.ts b/packages/vscode/genaisrc/genaiscript.d.ts
index f9f02e4454..5e88b248f2 100644
--- a/packages/vscode/genaisrc/genaiscript.d.ts
+++ b/packages/vscode/genaisrc/genaiscript.d.ts
@@ -1908,7 +1908,7 @@ interface ChatGenerationContext extends ChatTurnGenerationContext {
         options?: ChatParticipantOptions
     ): void
     defFileOutput(
-        pattern: string | string[],
+        pattern: ElementOrArray<string | WorkspaceFile>,
         description?: string,
         options?: FileOutputOptions
     ): void
@@ -2791,7 +2791,7 @@ declare function def(
  * @param options expectations about the generated file content
  */
 declare function defFileOutput(
-    pattern: string | string[],
+    pattern: ElementOrArray<string | WorkspaceFile>,
     description?: string,
     options?: FileOutputOptions
 ): void
diff --git a/slides/genaisrc/genaiscript.d.ts b/slides/genaisrc/genaiscript.d.ts
index f9f02e4454..5e88b248f2 100644
--- a/slides/genaisrc/genaiscript.d.ts
+++ b/slides/genaisrc/genaiscript.d.ts
@@ -1908,7 +1908,7 @@ interface ChatGenerationContext extends ChatTurnGenerationContext {
         options?: ChatParticipantOptions
     ): void
     defFileOutput(
-        pattern: string | string[],
+        pattern: ElementOrArray<string | WorkspaceFile>,
         description?: string,
         options?: FileOutputOptions
     ): void
@@ -2791,7 +2791,7 @@ declare function def(
  * @param options expectations about the generated file content
  */
 declare function defFileOutput(
-    pattern: string | string[],
+    pattern: ElementOrArray<string | WorkspaceFile>,
     description?: string,
     options?: FileOutputOptions
 ): void