diff --git a/CLAUDE.md b/CLAUDE.md
index 750be2f..ca79f9e 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -30,7 +30,7 @@ bun test src/supplier/supplier-scoring.test.ts
 ./node_modules/.bin/tsc --noEmit
 
 # ASIN lead-list pipeline (LLM-based)
-bun run src/index.ts input/leads.xlsx --out output/results.xlsx
+bun start leads.xlsx --out results.xlsx
 
 # Supplier UPC pipeline (deterministic)
 bun run upc-file --input input/supplier.xlsx --out output/supplier_ranked.xlsx
diff --git a/README.md b/README.md
index ea8ab6b..f418c0e 100644
--- a/README.md
+++ b/README.md
@@ -21,17 +21,19 @@ cp .env.example .env
 ## Usage
 
 ```bash
-bun run src/index.ts input/<input.csv|xlsx> [--out output/results.xlsx]
+bun start <input.csv|xlsx> [--out results.xlsx]
 ```
 
 Add `--claude` to use Anthropic Claude instead of local LM Studio for LLM analysis.
+Bare input and output filenames use the `input/` and `output/` directories. Pass a path containing a directory to override those defaults.
 
 Examples:
 
 ```bash
-bun run src/index.ts input/leads.xlsx
-bun run src/index.ts input/leads.csv --out output/results.xlsx
-bun run src/index.ts input/leads.xlsx --claude
+bun start leads.xlsx
+bun start leads.csv --out results.xlsx
+bun start leads.xlsx --claude
+bun start archive/leads.xlsx --out exports/results.xlsx
 ```
 
 Large-file behavior:
diff --git a/src/index.ts b/src/index.ts
index ee2efe0..7d89f54 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -14,6 +14,8 @@ import path from "node:path";
 import type { AnalysisResult } from "./types.ts";
 
 const INPUT_BATCH_SIZE = 50;
+const INPUT_DIR = "input";
+const OUTPUT_DIR = "output";
 
 function parseSellabilityArg(args: string[]): SellabilityFilter {
   const sellabilityArg = args.find((a) => a.startsWith("--sellability="));
@@ -45,7 +47,7 @@ function parseArgs(): {
   const args = process.argv.slice(2);
   const outputFile = readFlagValue(args, "--out", "--output");
   const useClaude = args.includes("--claude");
-  const inputFile = readInputFileArg(
+  const inputFileArg = readInputFileArg(
     args,
     "--out",
     "--output",
@@ -53,14 +55,19 @@ function parseArgs(): {
   );
   const sellability = parseSellabilityArg(args);
 
-  if (!inputFile) {
+  if (!inputFileArg) {
     console.error(
-      "Usage: bun run src/index.ts <input.csv|xlsx> [--out results.xlsx|--output results.xlsx] [--sellability available|all] [--claude]",
+      "Usage: bun run src/index.ts <input.csv|xlsx> [--out results.xlsx|--output results.xlsx] [--sellability available|all] [--claude]\nBare filenames are read from input/ and written to output/.",
     );
     process.exit(1);
   }
 
-  return { inputFile, outputFile, sellability, useClaude };
+  return {
+    inputFile: resolveInputPath(inputFileArg),
+    outputFile,
+    sellability,
+    useClaude,
+  };
 }
 
 function readFlagValue(args: string[], ...flags: string[]): string | undefined {
@@ -101,11 +108,25 @@ function readInputFileArg(
   return undefined;
 }
 
+function isBareFilename(filePath: string): boolean {
+  return !path.isAbsolute(filePath) && !/[\\/]/.test(filePath);
+}
+
+function resolveInputPath(inputFile: string): string {
+  return isBareFilename(inputFile)
+    ? path.join(INPUT_DIR, inputFile)
+    : inputFile;
+}
+
 function resolveBaseOutputPath(inputFile: string, outputFile?: string): string {
-  if (outputFile) return outputFile;
+  if (outputFile) {
+    return isBareFilename(outputFile)
+      ? path.join(OUTPUT_DIR, outputFile)
+      : outputFile;
+  }
 
   const parsedInput = path.parse(inputFile);
-  return path.join("output", `${parsedInput.name}_results.xlsx`);
+  return path.join(OUTPUT_DIR, `${parsedInput.name}_results.xlsx`);
 }
 
 async function main() {