diff --git a/.github/workflows/ollama.yml b/.github/workflows/ollama.yml
index 39f50fe27e..08d7e24ac6 100644
--- a/.github/workflows/ollama.yml
+++ b/.github/workflows/ollama.yml
@@ -31,7 +31,10 @@ jobs:
             - name: start ollama
               run: yarn ollama:start
             - name: run summarize-ollama-phi3
-              run: yarn test:summarize --model ollama:phi3.5 --out ./temp/summarize-ollama-phi3
+              run: yarn test:summarize --model ollama:phi3.5:latest --out ./temp/summarize-ollama-phi3
               env:
-                  OLLAMA_HOST: "http://localhost:11434"                  
-
+                  OLLAMA_HOST: "http://localhost:11434"
+            - name: run convert-ollama-phi3
+              run: yarn cli convert summarize --model ollama:phi3.5:latest "packages/sample/src/rag/*.md" --cache-name sum
+              env:
+                  OLLAMA_HOST: "http://localhost:11434"
diff --git a/.gitignore b/.gitignore
index b64fd9926c..e73a63dc3b 100644
--- a/.gitignore
+++ b/.gitignore
@@ -31,3 +31,4 @@ packages/core/*.temp.*
 packages/sample/test.txt
 packages/sample/poems/*.txt
 packages/sample/src/rag/markdown.md.txt
+*.genai.md
diff --git a/docs/src/content/docs/reference/cli/commands.md b/docs/src/content/docs/reference/cli/commands.md
index 98220fc43b..9971f7cf66 100644
--- a/docs/src/content/docs/reference/cli/commands.md
+++ b/docs/src/content/docs/reference/cli/commands.md
@@ -49,7 +49,7 @@ Options:
   -mtc, --max-tool-calls <number>            maximum tool calls for the run
   -se, --seed <number>                       seed for the run
   -em, --embeddings-model <string>           embeddings model for the run
-  --cache                                    enable LLM result cache
+  -c, --cache                                enable LLM result cache
   -cn, --cache-name <name>                   custom cache file name
   -cs, --csv-separator <string>              csv separator (default: "\t")
   -ff, --fence-format <string>               fence format (choices: "xml", "markdown", "none")
@@ -129,6 +129,43 @@ Options:
   -h, --help  display help for command
 ```
 
+## `convert`
+
+```
+Usage: genaiscript convert [options] <script> [files...]
+
+Converts file through a GenAIScript. Each file is processed separately through
+the GenAIScript and the LLM output is saved to a <filename>.genai.md (or custom
+suffix).
+
+Options:
+  -s, --suffix <string>              suffix for converted files (default:
+                                     ".genai.md")
+  -rw, --rewrite                     rewrite input file with output
+  -cw, --cancel-word <string>        cancel word which allows the LLM to notify
+                                     to ignore output
+  -ef, --excluded-files <string...>  excluded files
+  -egi, --exclude-git-ignore         exclude files that are ignored through the
+                                     .gitignore file in the workspace root
+  -m, --model <string>               'large' model alias (default)
+  -sm, --small-model <string>        'small' alias model
+  -vm, --vision-model <string>       'vision' alias model
+  -ma, --model-alias <nameid...>     model alias as name=modelid
+  -ft, --fallback-tools              Enable prompt-based tools instead of
+                                     builtin LLM tool calling builtin tool
+                                     calls
+  -o, --out <string>                 output folder. Extra markdown fields for
+                                     output and trace will also be generated
+  --vars <namevalue...>              variables, as name=value, stored in
+                                     env.vars. Use environment variables
+                                     GENAISCRIPT_VAR_name=value to pass
+                                     variable through the environment
+  -c, --cache                        enable LLM result cache
+  -cn, --cache-name <name>           custom cache file name
+  -cc, --concurrency <number>        number of concurrent conversions
+  -h, --help                         display help for command
+```
+
 ## `scripts`
 
 ```
diff --git a/docs/src/content/docs/reference/cli/convert.mdx b/docs/src/content/docs/reference/cli/convert.mdx
new file mode 100644
index 0000000000..4dc1cf91e2
--- /dev/null
+++ b/docs/src/content/docs/reference/cli/convert.mdx
@@ -0,0 +1,83 @@
+---
+title: Convert
+description: Learn how to apply a script to many files and extract the output.
+sidebar:
+    order: 2
+keywords: CLI tool execution, genai script running, stdout streaming, file globing, environment configuration
+---
+
+Converts a set of files, separately, using a script.
+
+```bash
+npx genaiscript convert <script> "<files...>"
+```
+
+where `<script>` is the id or file path of the tool to run, and `<files...>` is the name of the spec file to run it on.
+Unlike `run` which works on all files at once, `convert` processes each file individually.
+
+## Files
+
+`convert` takes one or more [glob](<https://en.wikipedia.org/wiki/Glob_(programming)>) patterns to match files in the workspace.
+
+```bash sh
+npx genaiscript run <script> "**/*.md" "**/*.ts"
+```
+
+### --excluded-files &lt;files...&gt;
+
+Excludes the specified files from the file set.
+
+```sh "--excluded-files <excluded-files...>"
+npx genaiscript convert <script> <files> --excluded-files <excluded-files...>
+```
+
+### --exclude-git-ignore
+
+Exclude files ignored by the `.gitignore` file at the workspace root.
+
+```sh "--exclude-git-ignore"
+npx genaiscript convert <script> <files> --exclude-git-ignore
+```
+
+## Output
+
+The output of each file is saved to a new or existing file. You can control the logic to decide which part of the output to save where to save it.
+By default, a conversion result of a file `<filename>` is saved to a file `<filename>.genai.md`.
+
+### --suffix &lt;suffix&gt;
+
+The `--suffix` option allows you to specify a suffix to append to the output file name.
+
+```sh "--suffix .genai.txt"
+npx genaiscript convert <script> <files> --suffix .genai.txt
+```
+
+GenAIScript will "unfence" output in the markdown that match the suffix (after `.genai`) automatically. So if the LLM generates
+
+````markdown
+```txt
+:)
+```
+````
+
+The converted content in `<filename>.genai.txt` will be `:)`.
+
+### --rewrite
+
+This flag override `suffix` and tells GenAIScript to rewrite the original file with the converted content.
+
+```sh "--rewrite"
+npx genaiscript convert <script> <files> --rewrite
+```
+
+### --cancel-word &lt;word&gt;
+
+Specify the "ignore output, nothing to see here" keyword using the `-cw` flag.
+
+```sh '--cancel-word "<NO>"'
+npx genaiscript convert <script> <files> --cancel-word "<NO>"
+```
+
+## Read more
+
+The full list of options is available in the [CLI reference](/genaiscript/reference/cli/commands#convert).
diff --git a/docs/src/content/docs/reference/cli/run.mdx b/docs/src/content/docs/reference/cli/run.mdx
index b3c86be330..4ff50a19a6 100644
--- a/docs/src/content/docs/reference/cli/run.mdx
+++ b/docs/src/content/docs/reference/cli/run.mdx
@@ -12,7 +12,7 @@ Runs a script on files and streams the LLM output to stdout or a folder from the
 npx genaiscript run <script> "<files...>"
 ```
 
-where `<script>` is the id or file path of the tool to run, and `[spec]` is the name of the spec file to run it on.
+where `<script>` is the id or file path of the tool to run, and `<files...>` is the name of the spec file to run it on.
 
 Files can also include [glob](<https://en.wikipedia.org/wiki/Glob_(programming)>) pattern.
 
@@ -26,12 +26,6 @@ If multiple files are specified, all files are included in `env.files`.
 npx genaiscript run <script> "src/*.bicep" "src/*.ts"
 ```
 
-## Credentials
-
-The LLM connection configuration is read from environment variables or from a `.env` file in the workspace root directory.
-
-See [configuration](/genaiscript/getting-started/configuration).
-
 ## Files
 
 `run` takes one or more [glob](<https://en.wikipedia.org/wiki/Glob_(programming)>) patterns to match files in the workspace.
diff --git a/docs/src/content/docs/samples/sc.mdx b/docs/src/content/docs/samples/sc.mdx
index 885a8fde38..6fed20201f 100644
--- a/docs/src/content/docs/samples/sc.mdx
+++ b/docs/src/content/docs/samples/sc.mdx
@@ -17,64 +17,49 @@ Starting at the top of the script, we see that it's a GenAI script, which is evi
 ```ts
 script({
     title: "Spell checker",
-    system: ["system", "system.files", "system.diff"],
-    temperature: 0.1,
+    system: [
+        "system.output_plaintext",
+        "system.assistant",
+        "system.files",
+        "system.changelog",
+        "system.safety_jailbreak",
+        "system.safety_harmful_content",
+    ],
+    temperature: 0.2,
+    cache: "sc",
 })
 ```
 
 This block sets the title of the script to "Spell checker" and specifies that it uses several system prompts, such as file operations and diff generation. The `temperature` is set to `0.1`, indicating that the script will generate output with low creativity, thus favoring precision.
 
-### Fetching Files for Checking
-
-Next, we check for files to process, first from the environment and then from Git if none are provided.
-
-```ts
-let files = env.files
-if (files.length === 0) {
-    const gitStatus = await host.exec("git diff --name-only --cached")
-    files = await Promise.all(
-        gitStatus.stdout
-            .split(/\r?\n/g)
-            .filter((filename) => /\.(md|mdx)$/.test(filename))
-            .map(async (filename) => await workspace.readText(filename))
-    )
-}
-```
-
-In this block, we're assigning files from the `env` variable, which would contain any files passed to the script. If no files are provided, we execute a Git command to get a list of all cached (staged) modified files and filter them to include only `.md` and `.mdx` files. We then read the content of these files for processing.
-
 ### Defining the File Types to Work on
 
 Following this, there's a `def` call:
 
 ```ts
-def("FILES", files, { endsWith: [".md", ".mdx"] })
+def("FILES", files)
 ```
 
-This line defines `FILES` to be the array of files we gathered. The options object `{ endsWith: [".md", ".mdx"] }` tells GenAI that we're only interested in files ending with `.md` or `.mdx`.
+This line defines `FILES` to be the array of files we gathered.
 
 The `$`-prefixed backtick notation is used to write the prompt template:
 
 ```ts
-$`Fix the spelling and grammar of the content of FILES. Use diff format for small changes.
-
-- do NOT fix the frontmatter
-- do NOT fix code regions
-- do NOT fix \`code\` and \`\`\`code\`\`\`
+$`Fix the spelling and grammar of the content of ${files}. Return the full file with corrections
+If you find a spelling or grammar mistake, fix it. 
+If you do not find any mistakes, respond <NO> and nothing else.
+
+- only fix major errors
+- use a technical documentation tone
+- minimize changes; do NOT change the meaning of the content
+- if the grammar is good enough, do NOT change it
+- do NOT modify the frontmatter. THIS IS IMPORTANT.
+- do NOT modify code regions. THIS IS IMPORTANT.
+- do NOT fix \`code\` and \`\`\`code\`\`\` sections
 - in .mdx files, do NOT fix inline typescript code
 `
 ```
 
-This prompt instructs GenAI to fix spelling and grammar in the content of the defined `FILES`, outputting small changes in diff format. It also specifies constraints, such as not fixing the frontmatter, code regions, inline code in markdown, and inline TypeScript code in MDX files.
-
-Finally, there is a `defFileOutput` call:
-
-```ts
-defFileOutput(files, "fixed markdown or mdx files")
-```
-
-This call declares the intent that the script will generate "fixed markdown or mdx files" based on the input files.
-
 ## How to Run the Script with GenAIScript CLI
 
 Running this spell checker script is straightforward with the GenAIScript CLI. First, ensure you have the CLI installed by following the instructions in the [GenAIScript documentation](https://microsoft.github.io/genaiscript/getting-started/installation).
@@ -82,10 +67,10 @@ Running this spell checker script is straightforward with the GenAIScript CLI. F
 Once you have the CLI installed, navigate to your local copy of the script in your terminal or command line interface. Run the following command to execute the spell checker:
 
 ```shell
-genaiscript run sc
+genaiscript convert sc "**/*.md" --rewrite
 ```
 
-Remember, you do not need to specify the `.genai.mts` extension when using the `run` command.
+Remember, you do not need to specify the `.genai.mts` extension when using the `convert` command.
 
 And there you have it—a detailed walkthrough of a GenAI spell checker script for markdown files. Happy coding and perfecting your documents!
 
@@ -97,10 +82,10 @@ And there you have it—a detailed walkthrough of a GenAI spell checker script f
 
 The following measures are taken to ensure the safety of the generated content.
 
--   This script includes system prompts to prevent prompt injection and harmful content generation.
+- This script includes system prompts to prevent prompt injection and harmful content generation.
     - [system.safety_jailbreak](/genaiscript/reference/scripts/system#systemsafety_jailbreak)
     - [system.safety_harmful_content](/genaiscript/reference/scripts/system#systemsafety_harmful_content)
--   The generated description is saved to a file at a specific path, which allows for a manual review before committing the changes.
+- The generated description is saved to a file at a specific path, which allows for a manual review before committing the changes.
 
 Additional measures to further enhance safety would be to run [a model with a safety filter](https://learn.microsoft.com/en-us/azure/ai-services/openai/concepts/content-filter?tabs=warning%2Cuser-prompt%2Cpython-new)
 or validate the message with a [content safety service](/genaiscript/reference/scripts/content-safety).
diff --git a/package.json b/package.json
index 8bda92a067..f5143d07d8 100644
--- a/package.json
+++ b/package.json
@@ -72,6 +72,7 @@
         "gcm": "node packages/cli/built/genaiscript.cjs run gcm --model github:gpt-4o",
         "prd": "node packages/cli/built/genaiscript.cjs run prd -prd --model github:gpt-4o",
         "genai": "node packages/cli/built/genaiscript.cjs run",
+        "genai:convert": "node packages/cli/built/genaiscript.cjs convert",
         "genai:debug": "yarn compile-debug && node packages/cli/built/genaiscript.cjs run",
         "upgrade:deps": "zx scripts/upgrade-deps.mjs",
         "cli": "node packages/cli/built/genaiscript.cjs",
diff --git a/packages/cli/src/api.ts b/packages/cli/src/api.ts
index 486442d93f..7e72cd76e9 100644
--- a/packages/cli/src/api.ts
+++ b/packages/cli/src/api.ts
@@ -34,10 +34,7 @@ export async function run(
          */
         signal?: AbortSignal
     }
-): Promise<{
-    exitCode: number
-    result?: GenerationResult
-}> {
+): Promise<GenerationResult> {
     if (!scriptId) throw new Error("scriptId is required")
     if (typeof files === "string") files = [files]
 
diff --git a/packages/cli/src/cli.ts b/packages/cli/src/cli.ts
index 10faa5b536..a74de5c0fa 100644
--- a/packages/cli/src/cli.ts
+++ b/packages/cli/src/cli.ts
@@ -37,6 +37,7 @@ import {
     OPENAI_MAX_RETRY_DELAY,
     OPENAI_RETRY_DEFAULT_DEFAULT,
     OPENAI_MAX_RETRY_COUNT,
+    GENAI_MD_EXT,
 } from "../../core/src/constants" // Core constants
 import {
     errorMessage,
@@ -47,6 +48,7 @@ import {
 import { CORE_VERSION, GITHUB_REPO } from "../../core/src/version" // Core version and repository info
 import { logVerbose } from "../../core/src/util" // Utility logging
 import { semverSatisfies } from "../../core/src/semver" // Semantic version checking
+import { convertFiles } from "./convert"
 
 /**
  * Main function to initialize and run the CLI.
@@ -177,7 +179,7 @@ export async function cli() {
             "-em, --embeddings-model <string>",
             "embeddings model for the run"
         )
-        .option("--cache", "enable LLM result cache")
+        .option("-c, --cache", "enable LLM result cache")
         .option("-cn, --cache-name <name>", "custom cache file name")
         .option("-cs, --csv-separator <string>", "csv separator", "\t")
         .addOption(
@@ -245,6 +247,51 @@ export async function cli() {
         .description("Launch test viewer")
         .action(scriptTestsView) // Action to view the tests
 
+    program
+        .command("convert")
+        .description(
+            "Converts file through a GenAIScript. Each file is processed separately through the GenAIScript and the LLM output is saved to a <filename>.genai.md (or custom suffix)."
+        )
+        .arguments("<script> [files...]")
+        .option(
+            "-s, --suffix <string>",
+            "suffix for converted files",
+            GENAI_MD_EXT
+        )
+        .option("-rw, --rewrite", "rewrite input file with output")
+        .option(
+            "-cw, --cancel-word <string>",
+            "cancel word which allows the LLM to notify to ignore output"
+        )
+        .option("-ef, --excluded-files <string...>", "excluded files")
+        .option(
+            "-egi, --exclude-git-ignore",
+            "exclude files that are ignored through the .gitignore file in the workspace root"
+        )
+        .option("-m, --model <string>", "'large' model alias (default)")
+        .option("-sm, --small-model <string>", "'small' alias model")
+        .option("-vm, --vision-model <string>", "'vision' alias model")
+        .option("-ma, --model-alias <nameid...>", "model alias as name=modelid")
+        .option(
+            "-ft, --fallback-tools",
+            "Enable prompt-based tools instead of builtin LLM tool calling builtin tool calls"
+        )
+        .option(
+            "-o, --out <string>",
+            "output folder. Extra markdown fields for output and trace will also be generated"
+        )
+        .option(
+            "--vars <namevalue...>",
+            "variables, as name=value, stored in env.vars. Use environment variables GENAISCRIPT_VAR_name=value to pass variable through the environment"
+        )
+        .option("-c, --cache", "enable LLM result cache")
+        .option("-cn, --cache-name <name>", "custom cache file name")
+        .option(
+            "-cc, --concurrency <number>",
+            "number of concurrent conversions"
+        )
+        .action(convertFiles)
+
     // Define 'scripts' command group for script management tasks
     const scripts = program
         .command("scripts")
@@ -281,7 +328,7 @@ export async function cli() {
 
     // Define 'cache' command for cache management
     const cache = program.command("cache").description("Cache management")
-    const clear = cache
+    cache
         .command("clear")
         .description("Clear cache")
         .argument("[name]", "Name of the cache, tests")
diff --git a/packages/cli/src/convert.ts b/packages/cli/src/convert.ts
new file mode 100644
index 0000000000..ca0b985b6d
--- /dev/null
+++ b/packages/cli/src/convert.ts
@@ -0,0 +1,180 @@
+import {
+    FILES_NOT_FOUND_ERROR_CODE,
+    GENAI_ANY_REGEX,
+    GENAI_MD_EXT,
+    HTTPS_REGEX,
+} from "../../core/src/constants"
+import { filePathOrUrlToWorkspaceFile, tryReadText } from "../../core/src/fs"
+import { host } from "../../core/src/host"
+import { MarkdownTrace, TraceOptions } from "../../core/src/trace"
+import {
+    logError,
+    logInfo,
+    logVerbose,
+    normalizeInt,
+} from "../../core/src/util"
+import { buildProject } from "./build"
+import { run } from "./api"
+import { writeText } from "../../core/src/fs"
+import { PromptScriptRunOptions } from "./main"
+import { PLimitPromiseQueue } from "../../core/src/concurrency"
+import { createPatch } from "diff"
+import { unfence } from "../../core/src/fence"
+
+export async function convertFiles(
+    scriptId: string,
+    fileGlobs: string[],
+    options: Partial<PromptScriptRunOptions> & {
+        suffix?: string
+        rewrite?: boolean
+        cancelWord?: string
+        concurrency?: string
+    } & TraceOptions
+): Promise<void> {
+    const {
+        trace = new MarkdownTrace(),
+        excludedFiles,
+        excludeGitIgnore,
+        suffix = GENAI_MD_EXT,
+        rewrite,
+        cancelWord,
+        concurrency,
+        ...restOptions
+    } = options || {}
+    const fail = (msg: string, exitCode: number, url?: string) => {
+        throw new Error(msg)
+    }
+    const { resolve } = host.path
+
+    const toolFiles: string[] = []
+    if (GENAI_ANY_REGEX.test(scriptId)) toolFiles.push(scriptId)
+    const prj = await buildProject({
+        toolFiles,
+    })
+    const script = prj.scripts.find(
+        (t) =>
+            t.id === scriptId ||
+            (t.filename &&
+                GENAI_ANY_REGEX.test(scriptId) &&
+                resolve(t.filename) === resolve(scriptId))
+    )
+    if (!script) throw new Error(`script ${scriptId} not found`)
+
+    // resolve files
+    const resolvedFiles = new Set<string>()
+    for (let arg of fileGlobs) {
+        if (HTTPS_REGEX.test(arg)) {
+            resolvedFiles.add(arg)
+            continue
+        }
+        const stats = await host.statFile(arg)
+        if (stats?.type === "directory") arg = host.path.join(arg, "**", "*")
+        const ffs = await host.findFiles(arg, {
+            applyGitIgnore: excludeGitIgnore,
+        })
+        if (!ffs?.length) {
+            return fail(
+                `no files matching ${arg} under ${process.cwd()}`,
+                FILES_NOT_FOUND_ERROR_CODE
+            )
+        }
+        for (const file of ffs) {
+            if (!rewrite && file.toLocaleLowerCase().endsWith(suffix)) continue
+            resolvedFiles.add(filePathOrUrlToWorkspaceFile(file))
+        }
+    }
+    if (excludedFiles?.length) {
+        for (const arg of excludedFiles) {
+            const ffs = await host.findFiles(arg)
+            for (const f of ffs)
+                resolvedFiles.delete(filePathOrUrlToWorkspaceFile(f))
+        }
+    }
+
+    // processing
+    const files = Array.from(resolvedFiles).map(
+        (filename) => ({ filename }) as WorkspaceFile
+    )
+
+    const p = new PLimitPromiseQueue(normalizeInt(concurrency) || 1)
+    await p.mapAll(files, async (file) => {
+        const outf = rewrite ? file.filename : file.filename + suffix
+        logInfo(`${file.filename} -> ${outf}`)
+        const fileTrace = trace.startTraceDetails(file.filename)
+        try {
+            // apply AI transformation
+            const result = await run(script.filename, file.filename, {
+                label: file.filename,
+                ...restOptions,
+            })
+            const { error } = result || {}
+            if (error) {
+                logError(error)
+                fileTrace.error(undefined, error)
+                return
+            }
+            if (result.status === "cancelled") {
+                logVerbose(`cancelled ${file.filename}`)
+                return
+            }
+            // LLM canceled
+            if (cancelWord && result?.text?.includes(cancelWord)) {
+                logVerbose(`cancel word detected, skipping ${file.filename}`)
+                return
+            }
+            logVerbose(Object.keys(result.fileEdits || {}).join("\n"))
+            // structured extraction
+            const fileEdit = Object.entries(result.fileEdits || {}).find(
+                ([fn]) => resolve(fn) === resolve(file.filename)
+            )?.[1]
+            //            if (!fileEdit) {
+            //              console.log({
+            //                filename: file.filename,
+            //              edits: result.fileEdits,
+            //        })
+            const suffixext = suffix.replace(/^.genai./i, ".")
+            const fence = result.fences.find((f) => f.language === suffixext)
+            let text: string = undefined
+            if (fileEdit?.after) {
+                if (fileEdit.validation?.schemaError) {
+                    logError("schema validation error")
+                    logVerbose(fileEdit.validation.schemaError)
+                    fileTrace.error(undefined, fileEdit.validation.schemaError)
+                    return
+                }
+                text = fileEdit.after
+            }
+            if (text === undefined && fence) {
+                if (fence.validation?.schemaError) {
+                    logError("schema validation error")
+                    logVerbose(fence.validation.schemaError)
+                    fileTrace.error(undefined, fence.validation.schemaError)
+                    return
+                }
+                text = fence.content
+            }
+            if (text === undefined) text = unfence(result.text, "markdown")
+
+            // save file
+            const existing = await tryReadText(outf)
+            if (text && existing !== text) {
+                const patch = createPatch(
+                    outf,
+                    existing || "",
+                    text || "",
+                    undefined,
+                    undefined,
+                    {}
+                )
+                logVerbose(patch)
+                await writeText(outf, text)
+            }
+        } catch (error) {
+            logError(error)
+            fileTrace.error(undefined, error)
+        } finally {
+            logVerbose("")
+            trace.endDetails()
+        }
+    })
+}
diff --git a/packages/core/src/constants.ts b/packages/core/src/constants.ts
index f4a39de951..dd417c1d46 100644
--- a/packages/core/src/constants.ts
+++ b/packages/core/src/constants.ts
@@ -26,6 +26,7 @@ export const CLI_JS = TOOL_ID + ".cjs"
 export const GENAI_SRC = "genaisrc"
 export const GENAI_JS_EXT = ".genai.js"
 export const GENAI_MJS_EXT = ".genai.mjs"
+export const GENAI_MD_EXT = ".genai.md"
 export const GENAI_ANYJS_GLOB =
     "**/*{.genai.js,.genai.mjs,.genai.ts,.genai.mts,.prompty}"
 export const GENAI_ANY_REGEX = /\.(genai\.(ts|mts|mjs|js)|prompty)$/i
diff --git a/packages/core/src/fs.ts b/packages/core/src/fs.ts
index c37d35800f..2575f386e0 100644
--- a/packages/core/src/fs.ts
+++ b/packages/core/src/fs.ts
@@ -22,7 +22,7 @@ export async function writeText(fn: string, content: string) {
 
 export async function fileExists(fn: string) {
     try {
-        return await host.readFile(fn) !== undefined
+        return (await host.readFile(fn)) !== undefined
     } catch {
         return false
     }
diff --git a/packages/core/src/ollama.ts b/packages/core/src/ollama.ts
index 99b5a89f98..9d18e62fe2 100644
--- a/packages/core/src/ollama.ts
+++ b/packages/core/src/ollama.ts
@@ -51,6 +51,7 @@ const OllamaCompletion: ChatCompletionHandler = async (
                     body: JSON.stringify({ name: model, stream: false }),
                 })
                 if (!res.ok) {
+                    trace.error(`ollama: failed to pull model ${model}`)
                     throw new Error(
                         `Failed to pull model ${model}: ${res.status} ${res.statusText}`
                     )
diff --git a/packages/core/src/usage.ts b/packages/core/src/usage.ts
index 3f1ada1835..8e045adfc0 100644
--- a/packages/core/src/usage.ts
+++ b/packages/core/src/usage.ts
@@ -258,8 +258,8 @@ export class GenerationStats {
         const c = this.cost()
         if (this.model && isNaN(c) && isCosteable(this.model))
             unknowns.add(this.model)
-        if (this.resolvedModel || c) {
-            const au = this.accumulatedUsage()
+        const au = this.accumulatedUsage()
+        if (au?.total_tokens > 0 && (this.resolvedModel || c)) {
             logVerbose(
                 `${indent}${this.label ? `${this.label} (${this.resolvedModel})` : this.resolvedModel}> ${au.total_tokens} tokens (${au.prompt_tokens} -> ${au.completion_tokens}) ${renderCost(c)}`
             )
diff --git a/packages/sample/genaisrc/samples/sc.genai.mts b/packages/sample/genaisrc/samples/sc.genai.mts
index 022dd40c41..1250d06856 100644
--- a/packages/sample/genaisrc/samples/sc.genai.mts
+++ b/packages/sample/genaisrc/samples/sc.genai.mts
@@ -1,63 +1,28 @@
 script({
     title: "Spell checker",
-    parameters: {
-        concurrency: {
-            type: "number",
-            description: "Number of concurrent jobs",
-            default: 1,
-        },
-    },
+    system: [
+        "system.output_plaintext",
+        "system.assistant",
+        "system.files",
+        "system.changelog",
+        "system.safety_jailbreak",
+        "system.safety_harmful_content",
+    ],
+    temperature: 0.2,
+    cache: "sc",
 })
-const { concurrency } = env.vars
+const files = def("FILES", env.files)
 
-// Get files from environment or modified files from Git if none provided
-let files = env.files
-if (files.length === 0) {
-    files = await git.listFiles("staged", {
-        paths: ["*.md", "*.mdx"],
-    })
-    if (!files.length)
-        files = await git.listFiles("modified-base", {
-            paths: ["*.md", "*.mdx"],
-        })
-}
+$`Fix the spelling and grammar of the content of ${files}. Return the full file with corrections
+If you find a spelling or grammar mistake, fix it. 
+If you do not find any mistakes, respond <NO> and nothing else.
 
-files = files.filter(({ filename }) => /.mdx?$/i.test(filename))
-const jobs = host.promiseQueue(concurrency)
-await jobs.mapAll(
-    files,
-    async (file) =>
-        await runPrompt(
-            (ctx) => {
-                ctx.def("FILES", file)
-                ctx.$`Analyze the spelling and grammar of the content of FILES.
-        If you find a spelling or grammar mistake, fix it. Use CHANGELOG file format for small changes.
-        If you do not find any mistakes, respond <NO> and nothing else.
-        
-        - only fix major errors
-        - use a technical documentation tone
-        - minimize changes; do NOT change the meaning of the content
-        - if the grammar is good enough, do NOT change it
-        - do NOT modify the frontmatter. THIS IS IMPORTANT.
-        - do NOT modify code regions. THIS IS IMPORTANT.
-        - do NOT fix \`code\` and \`\`\`code\`\`\` sections
-        - in .mdx files, do NOT fix inline typescript code
-        `
-
-                ctx.defFileOutput(files, "fixed markdown or mdx files")
-            },
-            {
-                label: `spell check ${file.filename}`,
-                model: "large",
-                system: [
-                    "system.assistant",
-                    "system.files",
-                    "system.changelog",
-                    "system.safety_jailbreak",
-                    "system.safety_harmful_content",
-                ],
-                temperature: 0.2,
-                cache: "sc",
-            }
-        )
-)
+- only fix major errors
+- use a technical documentation tone
+- minimize changes; do NOT change the meaning of the content
+- if the grammar is good enough, do NOT change it
+- do NOT modify the frontmatter. THIS IS IMPORTANT.
+- do NOT modify code regions. THIS IS IMPORTANT.
+- do NOT fix \`code\` and \`\`\`code\`\`\` sections
+- in .mdx files, do NOT fix inline typescript code
+`
diff --git a/packages/sample/src/rag/markdown.md b/packages/sample/src/rag/markdown.md
index 1105982132..962bcb24d1 100644
--- a/packages/sample/src/rag/markdown.md
+++ b/packages/sample/src/rag/markdown.md
@@ -1,6 +1,6 @@
 What is Markdown?
- Markdown is a lightweight markup language that you can use to add formatting elements to plaintext text documents. Created by John Gruber in 2004, Markdown is now one of the world’s most popular markup languages. 
+Markdown is a lightweight markup language that you can use to add formatting elements to plaintext text documents. Created by John Gruber in 2004, Markdown is now one of the world’s most popular markup languages.
 
 Using Markdown is different than using a WYSIWYG editor. In an application like Microsoft Word, you click buttons to format words and phrases, and the changes are visible immediately. Markdown isn’t like that. When you create a Markdown-formatted file, you add Markdown syntax to the text to indicate which words and phrases should look different.
 
-For example, to denote a heading, you add a number sign before it (e.g., # Heading One). Or to make a phrase bold, you add two asterisks before and after it (e.g., **this text is bold**). It may take a while to get used to seeing Markdown syntax in your text, especially if you’re accustomed to WYSIWYG applications. The screenshot below shows a Markdown file displayed in the Visual Studio Code text editor....
+For ixample, to denote a heading, you add a number sign before it (e.g., # Heading One). Or to make a phrase bold, you add two asterisks before and after it (e.g., **this text is bold**). It may take a while to get used to seeing Markdown syntax in your text, especially if you’re accustomed to WYSIWYG applications. The screenshot below shows a Markdown file displayed in the Visual Studio Code text editor....