diff --git a/docs/genaisrc/genaiscript.d.ts b/docs/genaisrc/genaiscript.d.ts
index d9596b1677..a726567079 100644
--- a/docs/genaisrc/genaiscript.d.ts
+++ b/docs/genaisrc/genaiscript.d.ts
@@ -83,6 +83,7 @@ type SystemPromptId = OptionsOrString<
     | "system.explanations"
     | "system.files"
     | "system.files_schema"
+    | "system.fs_diff_files"
     | "system.fs_find_files"
     | "system.fs_read_file"
     | "system.git"
@@ -112,6 +113,7 @@ type SystemToolId = OptionsOrString<
     | "agent_github"
     | "agent_interpreter"
     | "agent_user_input"
+    | "fs_diff_files"
     | "fs_find_files"
     | "fs_read_file"
     | "git_branch_current"
@@ -1242,6 +1244,11 @@ interface Parsers {
      * Renders a jinja template
      */
     jinja(text: string | WorkspaceFile, data: Record<string, any>): string
+
+    /**
+     * Computes a diff between two files
+     */
+    diff(left: WorkspaceFile, right: WorkspaceFile, options?: DefDiffOptions): string
 }
 
 interface AICIGenOptions {
diff --git a/docs/src/components/BuiltinTools.mdx b/docs/src/components/BuiltinTools.mdx
index 7a7842505e..b7c58b17a3 100644
--- a/docs/src/components/BuiltinTools.mdx
+++ b/docs/src/components/BuiltinTools.mdx
@@ -11,6 +11,7 @@ import { LinkCard } from '@astrojs/starlight/components';
 <LinkCard title="agent_github" description="Agent that can query GitHub  to accomplish tasks" href="/genaiscript/reference/scripts/system#systemagent_github" />
 <LinkCard title="agent_interpreter" description="Run code interpreters for Python, Math. Use this agent to ground computation questions." href="/genaiscript/reference/scripts/system#systemagent_interpreter" />
 <LinkCard title="agent_user_input" description="Ask user for input to confirm, select or answer a question." href="/genaiscript/reference/scripts/system#systemagent_user_input" />
+<LinkCard title="fs_diff_files" description="Computes a diff between two files." href="/genaiscript/reference/scripts/system#systemfs_diff_files" />
 <LinkCard title="fs_find_files" description="Finds file matching a glob pattern. Use pattern to specify a regular expression to search for in the file content." href="/genaiscript/reference/scripts/system#systemfs_find_files" />
 <LinkCard title="fs_read_file" description="Reads a file as text from the file system. Returns undefined if the file does not exist." href="/genaiscript/reference/scripts/system#systemfs_read_file" />
 <LinkCard title="git_branch_current" description="Gets the current branch." href="/genaiscript/reference/scripts/system#systemgit" />
diff --git a/docs/src/content/docs/reference/scripts/system.mdx b/docs/src/content/docs/reference/scripts/system.mdx
index 0310942d63..2ad84a3271 100644
--- a/docs/src/content/docs/reference/scripts/system.mdx
+++ b/docs/src/content/docs/reference/scripts/system.mdx
@@ -143,6 +143,7 @@ defTool(
                     "system.explanations",
                     "system.fs_find_files",
                     "system.fs_read_file",
+                    "system.fs_diff_files",
                     "system.retrieval_fuzz_search",
                     "system.md_frontmatter",
                 ],
@@ -652,6 +653,51 @@ def(`File ${folder}/data.json`, `...`, {
 `````
 
 
+### `system.fs_diff_files`
+
+File Diff Files
+
+Tool to compute a diff betweeen two files.
+
+-  tool `fs_diff_files`: Computes a diff between two files.
+
+`````js wrap title="system.fs_diff_files"
+system({
+    title: "File Diff Files",
+    description: "Tool to compute a diff betweeen two files.",
+})
+
+defTool(
+    "fs_diff_files",
+    "Computes a diff between two files.",
+    {
+        type: "object",
+        properties: {
+            filename: {
+                type: "string",
+                description:
+                    "Path of the file to compare, relative to the workspace.",
+            },
+            otherfilename: {
+                type: "string",
+                description:
+                    "Path of the other file to compare, relative to the workspace.",
+            },
+        },
+        required: ["filename"],
+    },
+    async (args) => {
+        const { context, filename, otherfilename } = args
+        context.log(`diff: ${filename} ${filename}`)
+        const f = await workspace.readText(filename)
+        const of = await workspace.readText(otherfilename)
+        return parsers.diff(f, of)
+    }
+)
+
+`````
+
+
 ### `system.fs_find_files`
 
 File find files
diff --git a/genaisrc/genaiscript.d.ts b/genaisrc/genaiscript.d.ts
index d9596b1677..a726567079 100644
--- a/genaisrc/genaiscript.d.ts
+++ b/genaisrc/genaiscript.d.ts
@@ -83,6 +83,7 @@ type SystemPromptId = OptionsOrString<
     | "system.explanations"
     | "system.files"
     | "system.files_schema"
+    | "system.fs_diff_files"
     | "system.fs_find_files"
     | "system.fs_read_file"
     | "system.git"
@@ -112,6 +113,7 @@ type SystemToolId = OptionsOrString<
     | "agent_github"
     | "agent_interpreter"
     | "agent_user_input"
+    | "fs_diff_files"
     | "fs_find_files"
     | "fs_read_file"
     | "git_branch_current"
@@ -1242,6 +1244,11 @@ interface Parsers {
      * Renders a jinja template
      */
     jinja(text: string | WorkspaceFile, data: Record<string, any>): string
+
+    /**
+     * Computes a diff between two files
+     */
+    diff(left: WorkspaceFile, right: WorkspaceFile, options?: DefDiffOptions): string
 }
 
 interface AICIGenOptions {
diff --git a/packages/auto/genaiscript.d.ts b/packages/auto/genaiscript.d.ts
index d9596b1677..a726567079 100644
--- a/packages/auto/genaiscript.d.ts
+++ b/packages/auto/genaiscript.d.ts
@@ -83,6 +83,7 @@ type SystemPromptId = OptionsOrString<
     | "system.explanations"
     | "system.files"
     | "system.files_schema"
+    | "system.fs_diff_files"
     | "system.fs_find_files"
     | "system.fs_read_file"
     | "system.git"
@@ -112,6 +113,7 @@ type SystemToolId = OptionsOrString<
     | "agent_github"
     | "agent_interpreter"
     | "agent_user_input"
+    | "fs_diff_files"
     | "fs_find_files"
     | "fs_read_file"
     | "git_branch_current"
@@ -1242,6 +1244,11 @@ interface Parsers {
      * Renders a jinja template
      */
     jinja(text: string | WorkspaceFile, data: Record<string, any>): string
+
+    /**
+     * Computes a diff between two files
+     */
+    diff(left: WorkspaceFile, right: WorkspaceFile, options?: DefDiffOptions): string
 }
 
 interface AICIGenOptions {
diff --git a/packages/core/src/genaisrc/genaiscript.d.ts b/packages/core/src/genaisrc/genaiscript.d.ts
index d9596b1677..a726567079 100644
--- a/packages/core/src/genaisrc/genaiscript.d.ts
+++ b/packages/core/src/genaisrc/genaiscript.d.ts
@@ -83,6 +83,7 @@ type SystemPromptId = OptionsOrString<
     | "system.explanations"
     | "system.files"
     | "system.files_schema"
+    | "system.fs_diff_files"
     | "system.fs_find_files"
     | "system.fs_read_file"
     | "system.git"
@@ -112,6 +113,7 @@ type SystemToolId = OptionsOrString<
     | "agent_github"
     | "agent_interpreter"
     | "agent_user_input"
+    | "fs_diff_files"
     | "fs_find_files"
     | "fs_read_file"
     | "git_branch_current"
@@ -1242,6 +1244,11 @@ interface Parsers {
      * Renders a jinja template
      */
     jinja(text: string | WorkspaceFile, data: Record<string, any>): string
+
+    /**
+     * Computes a diff between two files
+     */
+    diff(left: WorkspaceFile, right: WorkspaceFile, options?: DefDiffOptions): string
 }
 
 interface AICIGenOptions {
diff --git a/packages/core/src/genaisrc/system.agent_fs.genai.mjs b/packages/core/src/genaisrc/system.agent_fs.genai.mjs
index 7ba3b86f43..f5f5879793 100644
--- a/packages/core/src/genaisrc/system.agent_fs.genai.mjs
+++ b/packages/core/src/genaisrc/system.agent_fs.genai.mjs
@@ -36,6 +36,7 @@ defTool(
                     "system.explanations",
                     "system.fs_find_files",
                     "system.fs_read_file",
+                    "system.fs_diff_files",
                     "system.retrieval_fuzz_search",
                     "system.md_frontmatter",
                 ],
diff --git a/packages/core/src/genaisrc/system.fs_diff_files.genai.mjs b/packages/core/src/genaisrc/system.fs_diff_files.genai.mjs
new file mode 100644
index 0000000000..b30fd2743e
--- /dev/null
+++ b/packages/core/src/genaisrc/system.fs_diff_files.genai.mjs
@@ -0,0 +1,32 @@
+system({
+    title: "File Diff Files",
+    description: "Tool to compute a diff betweeen two files.",
+})
+
+defTool(
+    "fs_diff_files",
+    "Computes a diff between two files.",
+    {
+        type: "object",
+        properties: {
+            filename: {
+                type: "string",
+                description:
+                    "Path of the file to compare, relative to the workspace.",
+            },
+            otherfilename: {
+                type: "string",
+                description:
+                    "Path of the other file to compare, relative to the workspace.",
+            },
+        },
+        required: ["filename"],
+    },
+    async (args) => {
+        const { context, filename, otherfilename } = args
+        context.log(`diff: ${filename} ${filename}`)
+        const f = await workspace.readText(filename)
+        const of = await workspace.readText(otherfilename)
+        return parsers.diff(f, of)
+    }
+)
diff --git a/packages/core/src/genaisrc/system.fs_find_files.genai.js b/packages/core/src/genaisrc/system.fs_find_files.genai.mjs
similarity index 100%
rename from packages/core/src/genaisrc/system.fs_find_files.genai.js
rename to packages/core/src/genaisrc/system.fs_find_files.genai.mjs
diff --git a/packages/core/src/genaisrc/system.fs_read_file.genai.js b/packages/core/src/genaisrc/system.fs_read_file.genai.mjs
similarity index 100%
rename from packages/core/src/genaisrc/system.fs_read_file.genai.js
rename to packages/core/src/genaisrc/system.fs_read_file.genai.mjs
diff --git a/packages/core/src/parsers.ts b/packages/core/src/parsers.ts
index 0a6ca302ee..c4971bded3 100644
--- a/packages/core/src/parsers.ts
+++ b/packages/core/src/parsers.ts
@@ -25,6 +25,7 @@ import { resolveFileContent } from "./file"
 import { resolveTokenEncoder } from "./encoders"
 import { mustacheRender } from "./mustache"
 import { jinjaRender } from "./jinja"
+import { createDiff, llmifyDiff } from "./diff"
 
 export async function createParsers(options: {
     trace: MarkdownTrace
@@ -115,5 +116,6 @@ export async function createParsers(options: {
             const f = filenameOrFileToContent(file)
             return jinjaRender(f, data)
         },
+        diff: (f1, f2) => llmifyDiff(createDiff(f1, f2)),
     })
 }
diff --git a/packages/core/src/types/prompt_template.d.ts b/packages/core/src/types/prompt_template.d.ts
index 765b14a6e8..19d97f770e 100644
--- a/packages/core/src/types/prompt_template.d.ts
+++ b/packages/core/src/types/prompt_template.d.ts
@@ -1170,6 +1170,11 @@ interface Parsers {
      * Renders a jinja template
      */
     jinja(text: string | WorkspaceFile, data: Record<string, any>): string
+
+    /**
+     * Computes a diff between two files
+     */
+    diff(left: WorkspaceFile, right: WorkspaceFile, options?: DefDiffOptions): string
 }
 
 interface AICIGenOptions {
diff --git a/packages/sample/genaisrc/blog/genaiscript.d.ts b/packages/sample/genaisrc/blog/genaiscript.d.ts
index d9596b1677..a726567079 100644
--- a/packages/sample/genaisrc/blog/genaiscript.d.ts
+++ b/packages/sample/genaisrc/blog/genaiscript.d.ts
@@ -83,6 +83,7 @@ type SystemPromptId = OptionsOrString<
     | "system.explanations"
     | "system.files"
     | "system.files_schema"
+    | "system.fs_diff_files"
     | "system.fs_find_files"
     | "system.fs_read_file"
     | "system.git"
@@ -112,6 +113,7 @@ type SystemToolId = OptionsOrString<
     | "agent_github"
     | "agent_interpreter"
     | "agent_user_input"
+    | "fs_diff_files"
     | "fs_find_files"
     | "fs_read_file"
     | "git_branch_current"
@@ -1242,6 +1244,11 @@ interface Parsers {
      * Renders a jinja template
      */
     jinja(text: string | WorkspaceFile, data: Record<string, any>): string
+
+    /**
+     * Computes a diff between two files
+     */
+    diff(left: WorkspaceFile, right: WorkspaceFile, options?: DefDiffOptions): string
 }
 
 interface AICIGenOptions {
diff --git a/packages/sample/genaisrc/files.genai.js b/packages/sample/genaisrc/files.genai.mjs
similarity index 54%
rename from packages/sample/genaisrc/files.genai.js
rename to packages/sample/genaisrc/files.genai.mjs
index 75dc4ed9d4..ef712b66fe 100644
--- a/packages/sample/genaisrc/files.genai.js
+++ b/packages/sample/genaisrc/files.genai.mjs
@@ -1,7 +1,7 @@
 script({
     model: "gpt-3.5-turbo",
     system: ["system", "system.files"],
-    tests: {}
+    tests: {},
 })
 
-$`Generate a poem and save it in a file "poem.txt".`
\ No newline at end of file
+$`Generate a poem and save it in a file "poem.txt".`
diff --git a/packages/sample/genaisrc/genaiscript.d.ts b/packages/sample/genaisrc/genaiscript.d.ts
index d9596b1677..a726567079 100644
--- a/packages/sample/genaisrc/genaiscript.d.ts
+++ b/packages/sample/genaisrc/genaiscript.d.ts
@@ -83,6 +83,7 @@ type SystemPromptId = OptionsOrString<
     | "system.explanations"
     | "system.files"
     | "system.files_schema"
+    | "system.fs_diff_files"
     | "system.fs_find_files"
     | "system.fs_read_file"
     | "system.git"
@@ -112,6 +113,7 @@ type SystemToolId = OptionsOrString<
     | "agent_github"
     | "agent_interpreter"
     | "agent_user_input"
+    | "fs_diff_files"
     | "fs_find_files"
     | "fs_read_file"
     | "git_branch_current"
@@ -1242,6 +1244,11 @@ interface Parsers {
      * Renders a jinja template
      */
     jinja(text: string | WorkspaceFile, data: Record<string, any>): string
+
+    /**
+     * Computes a diff between two files
+     */
+    diff(left: WorkspaceFile, right: WorkspaceFile, options?: DefDiffOptions): string
 }
 
 interface AICIGenOptions {
diff --git a/packages/sample/genaisrc/node/genaiscript.d.ts b/packages/sample/genaisrc/node/genaiscript.d.ts
index d9596b1677..a726567079 100644
--- a/packages/sample/genaisrc/node/genaiscript.d.ts
+++ b/packages/sample/genaisrc/node/genaiscript.d.ts
@@ -83,6 +83,7 @@ type SystemPromptId = OptionsOrString<
     | "system.explanations"
     | "system.files"
     | "system.files_schema"
+    | "system.fs_diff_files"
     | "system.fs_find_files"
     | "system.fs_read_file"
     | "system.git"
@@ -112,6 +113,7 @@ type SystemToolId = OptionsOrString<
     | "agent_github"
     | "agent_interpreter"
     | "agent_user_input"
+    | "fs_diff_files"
     | "fs_find_files"
     | "fs_read_file"
     | "git_branch_current"
@@ -1242,6 +1244,11 @@ interface Parsers {
      * Renders a jinja template
      */
     jinja(text: string | WorkspaceFile, data: Record<string, any>): string
+
+    /**
+     * Computes a diff between two files
+     */
+    diff(left: WorkspaceFile, right: WorkspaceFile, options?: DefDiffOptions): string
 }
 
 interface AICIGenOptions {
diff --git a/packages/sample/genaisrc/python/genaiscript.d.ts b/packages/sample/genaisrc/python/genaiscript.d.ts
index d9596b1677..a726567079 100644
--- a/packages/sample/genaisrc/python/genaiscript.d.ts
+++ b/packages/sample/genaisrc/python/genaiscript.d.ts
@@ -83,6 +83,7 @@ type SystemPromptId = OptionsOrString<
     | "system.explanations"
     | "system.files"
     | "system.files_schema"
+    | "system.fs_diff_files"
     | "system.fs_find_files"
     | "system.fs_read_file"
     | "system.git"
@@ -112,6 +113,7 @@ type SystemToolId = OptionsOrString<
     | "agent_github"
     | "agent_interpreter"
     | "agent_user_input"
+    | "fs_diff_files"
     | "fs_find_files"
     | "fs_read_file"
     | "git_branch_current"
@@ -1242,6 +1244,11 @@ interface Parsers {
      * Renders a jinja template
      */
     jinja(text: string | WorkspaceFile, data: Record<string, any>): string
+
+    /**
+     * Computes a diff between two files
+     */
+    diff(left: WorkspaceFile, right: WorkspaceFile, options?: DefDiffOptions): string
 }
 
 interface AICIGenOptions {
diff --git a/packages/sample/genaisrc/style/genaiscript.d.ts b/packages/sample/genaisrc/style/genaiscript.d.ts
index d9596b1677..a726567079 100644
--- a/packages/sample/genaisrc/style/genaiscript.d.ts
+++ b/packages/sample/genaisrc/style/genaiscript.d.ts
@@ -83,6 +83,7 @@ type SystemPromptId = OptionsOrString<
     | "system.explanations"
     | "system.files"
     | "system.files_schema"
+    | "system.fs_diff_files"
     | "system.fs_find_files"
     | "system.fs_read_file"
     | "system.git"
@@ -112,6 +113,7 @@ type SystemToolId = OptionsOrString<
     | "agent_github"
     | "agent_interpreter"
     | "agent_user_input"
+    | "fs_diff_files"
     | "fs_find_files"
     | "fs_read_file"
     | "git_branch_current"
@@ -1242,6 +1244,11 @@ interface Parsers {
      * Renders a jinja template
      */
     jinja(text: string | WorkspaceFile, data: Record<string, any>): string
+
+    /**
+     * Computes a diff between two files
+     */
+    diff(left: WorkspaceFile, right: WorkspaceFile, options?: DefDiffOptions): string
 }
 
 interface AICIGenOptions {
diff --git a/packages/sample/src/aici/genaiscript.d.ts b/packages/sample/src/aici/genaiscript.d.ts
index d9596b1677..a726567079 100644
--- a/packages/sample/src/aici/genaiscript.d.ts
+++ b/packages/sample/src/aici/genaiscript.d.ts
@@ -83,6 +83,7 @@ type SystemPromptId = OptionsOrString<
     | "system.explanations"
     | "system.files"
     | "system.files_schema"
+    | "system.fs_diff_files"
     | "system.fs_find_files"
     | "system.fs_read_file"
     | "system.git"
@@ -112,6 +113,7 @@ type SystemToolId = OptionsOrString<
     | "agent_github"
     | "agent_interpreter"
     | "agent_user_input"
+    | "fs_diff_files"
     | "fs_find_files"
     | "fs_read_file"
     | "git_branch_current"
@@ -1242,6 +1244,11 @@ interface Parsers {
      * Renders a jinja template
      */
     jinja(text: string | WorkspaceFile, data: Record<string, any>): string
+
+    /**
+     * Computes a diff between two files
+     */
+    diff(left: WorkspaceFile, right: WorkspaceFile, options?: DefDiffOptions): string
 }
 
 interface AICIGenOptions {
diff --git a/packages/sample/src/errors/genaiscript.d.ts b/packages/sample/src/errors/genaiscript.d.ts
index d9596b1677..a726567079 100644
--- a/packages/sample/src/errors/genaiscript.d.ts
+++ b/packages/sample/src/errors/genaiscript.d.ts
@@ -83,6 +83,7 @@ type SystemPromptId = OptionsOrString<
     | "system.explanations"
     | "system.files"
     | "system.files_schema"
+    | "system.fs_diff_files"
     | "system.fs_find_files"
     | "system.fs_read_file"
     | "system.git"
@@ -112,6 +113,7 @@ type SystemToolId = OptionsOrString<
     | "agent_github"
     | "agent_interpreter"
     | "agent_user_input"
+    | "fs_diff_files"
     | "fs_find_files"
     | "fs_read_file"
     | "git_branch_current"
@@ -1242,6 +1244,11 @@ interface Parsers {
      * Renders a jinja template
      */
     jinja(text: string | WorkspaceFile, data: Record<string, any>): string
+
+    /**
+     * Computes a diff between two files
+     */
+    diff(left: WorkspaceFile, right: WorkspaceFile, options?: DefDiffOptions): string
 }
 
 interface AICIGenOptions {
diff --git a/packages/sample/src/genaiscript.d.ts b/packages/sample/src/genaiscript.d.ts
index d9596b1677..a726567079 100644
--- a/packages/sample/src/genaiscript.d.ts
+++ b/packages/sample/src/genaiscript.d.ts
@@ -83,6 +83,7 @@ type SystemPromptId = OptionsOrString<
     | "system.explanations"
     | "system.files"
     | "system.files_schema"
+    | "system.fs_diff_files"
     | "system.fs_find_files"
     | "system.fs_read_file"
     | "system.git"
@@ -112,6 +113,7 @@ type SystemToolId = OptionsOrString<
     | "agent_github"
     | "agent_interpreter"
     | "agent_user_input"
+    | "fs_diff_files"
     | "fs_find_files"
     | "fs_read_file"
     | "git_branch_current"
@@ -1242,6 +1244,11 @@ interface Parsers {
      * Renders a jinja template
      */
     jinja(text: string | WorkspaceFile, data: Record<string, any>): string
+
+    /**
+     * Computes a diff between two files
+     */
+    diff(left: WorkspaceFile, right: WorkspaceFile, options?: DefDiffOptions): string
 }
 
 interface AICIGenOptions {
diff --git a/packages/sample/src/makecode/genaiscript.d.ts b/packages/sample/src/makecode/genaiscript.d.ts
index d9596b1677..a726567079 100644
--- a/packages/sample/src/makecode/genaiscript.d.ts
+++ b/packages/sample/src/makecode/genaiscript.d.ts
@@ -83,6 +83,7 @@ type SystemPromptId = OptionsOrString<
     | "system.explanations"
     | "system.files"
     | "system.files_schema"
+    | "system.fs_diff_files"
     | "system.fs_find_files"
     | "system.fs_read_file"
     | "system.git"
@@ -112,6 +113,7 @@ type SystemToolId = OptionsOrString<
     | "agent_github"
     | "agent_interpreter"
     | "agent_user_input"
+    | "fs_diff_files"
     | "fs_find_files"
     | "fs_read_file"
     | "git_branch_current"
@@ -1242,6 +1244,11 @@ interface Parsers {
      * Renders a jinja template
      */
     jinja(text: string | WorkspaceFile, data: Record<string, any>): string
+
+    /**
+     * Computes a diff between two files
+     */
+    diff(left: WorkspaceFile, right: WorkspaceFile, options?: DefDiffOptions): string
 }
 
 interface AICIGenOptions {
diff --git a/packages/sample/src/tla/genaiscript.d.ts b/packages/sample/src/tla/genaiscript.d.ts
index d9596b1677..a726567079 100644
--- a/packages/sample/src/tla/genaiscript.d.ts
+++ b/packages/sample/src/tla/genaiscript.d.ts
@@ -83,6 +83,7 @@ type SystemPromptId = OptionsOrString<
     | "system.explanations"
     | "system.files"
     | "system.files_schema"
+    | "system.fs_diff_files"
     | "system.fs_find_files"
     | "system.fs_read_file"
     | "system.git"
@@ -112,6 +113,7 @@ type SystemToolId = OptionsOrString<
     | "agent_github"
     | "agent_interpreter"
     | "agent_user_input"
+    | "fs_diff_files"
     | "fs_find_files"
     | "fs_read_file"
     | "git_branch_current"
@@ -1242,6 +1244,11 @@ interface Parsers {
      * Renders a jinja template
      */
     jinja(text: string | WorkspaceFile, data: Record<string, any>): string
+
+    /**
+     * Computes a diff between two files
+     */
+    diff(left: WorkspaceFile, right: WorkspaceFile, options?: DefDiffOptions): string
 }
 
 interface AICIGenOptions {
diff --git a/packages/sample/src/vision/genaiscript.d.ts b/packages/sample/src/vision/genaiscript.d.ts
index d9596b1677..a726567079 100644
--- a/packages/sample/src/vision/genaiscript.d.ts
+++ b/packages/sample/src/vision/genaiscript.d.ts
@@ -83,6 +83,7 @@ type SystemPromptId = OptionsOrString<
     | "system.explanations"
     | "system.files"
     | "system.files_schema"
+    | "system.fs_diff_files"
     | "system.fs_find_files"
     | "system.fs_read_file"
     | "system.git"
@@ -112,6 +113,7 @@ type SystemToolId = OptionsOrString<
     | "agent_github"
     | "agent_interpreter"
     | "agent_user_input"
+    | "fs_diff_files"
     | "fs_find_files"
     | "fs_read_file"
     | "git_branch_current"
@@ -1242,6 +1244,11 @@ interface Parsers {
      * Renders a jinja template
      */
     jinja(text: string | WorkspaceFile, data: Record<string, any>): string
+
+    /**
+     * Computes a diff between two files
+     */
+    diff(left: WorkspaceFile, right: WorkspaceFile, options?: DefDiffOptions): string
 }
 
 interface AICIGenOptions {
diff --git a/packages/vscode/genaisrc/genaiscript.d.ts b/packages/vscode/genaisrc/genaiscript.d.ts
index d9596b1677..a726567079 100644
--- a/packages/vscode/genaisrc/genaiscript.d.ts
+++ b/packages/vscode/genaisrc/genaiscript.d.ts
@@ -83,6 +83,7 @@ type SystemPromptId = OptionsOrString<
     | "system.explanations"
     | "system.files"
     | "system.files_schema"
+    | "system.fs_diff_files"
     | "system.fs_find_files"
     | "system.fs_read_file"
     | "system.git"
@@ -112,6 +113,7 @@ type SystemToolId = OptionsOrString<
     | "agent_github"
     | "agent_interpreter"
     | "agent_user_input"
+    | "fs_diff_files"
     | "fs_find_files"
     | "fs_read_file"
     | "git_branch_current"
@@ -1242,6 +1244,11 @@ interface Parsers {
      * Renders a jinja template
      */
     jinja(text: string | WorkspaceFile, data: Record<string, any>): string
+
+    /**
+     * Computes a diff between two files
+     */
+    diff(left: WorkspaceFile, right: WorkspaceFile, options?: DefDiffOptions): string
 }
 
 interface AICIGenOptions {
diff --git a/slides/genaisrc/genaiscript.d.ts b/slides/genaisrc/genaiscript.d.ts
index d9596b1677..a726567079 100644
--- a/slides/genaisrc/genaiscript.d.ts
+++ b/slides/genaisrc/genaiscript.d.ts
@@ -83,6 +83,7 @@ type SystemPromptId = OptionsOrString<
     | "system.explanations"
     | "system.files"
     | "system.files_schema"
+    | "system.fs_diff_files"
     | "system.fs_find_files"
     | "system.fs_read_file"
     | "system.git"
@@ -112,6 +113,7 @@ type SystemToolId = OptionsOrString<
     | "agent_github"
     | "agent_interpreter"
     | "agent_user_input"
+    | "fs_diff_files"
     | "fs_find_files"
     | "fs_read_file"
     | "git_branch_current"
@@ -1242,6 +1244,11 @@ interface Parsers {
      * Renders a jinja template
      */
     jinja(text: string | WorkspaceFile, data: Record<string, any>): string
+
+    /**
+     * Computes a diff between two files
+     */
+    diff(left: WorkspaceFile, right: WorkspaceFile, options?: DefDiffOptions): string
 }
 
 interface AICIGenOptions {