diff --git a/README.md b/README.md
index 6b245b91a..b79b4a08f 100644
--- a/README.md
+++ b/README.md
@@ -152,6 +152,15 @@ pnpm install
 # Validate all YAML files
 pnpm validate
 
+# Validate only the files you touched: a fast pre-flight while editing.
+# It skips cross-file checks (duplicate IDs, supersedes targets and
+# cycles), so run the full `pnpm validate` above before committing.
+pnpm validate --files data/hardware/some-entry.yaml
+
+# Format all YAML files, or only the ones you touched
+pnpm format
+pnpm format data/hardware/some-entry.yaml
+
 # Build SQLite database locally
 pnpm build
 
diff --git a/schema/json/hardware.json b/schema/json/hardware.json
index df140f5f2..bbbebaf01 100644
--- a/schema/json/hardware.json
+++ b/schema/json/hardware.json
@@ -2394,7 +2394,7 @@
               "Left",
               "Right"
             ],
-            "description": "Physical position on the device. Defined in schema/io-positions.yaml."
+            "description": "Physical position on the device. Defined in schema/io-positions.yaml. Required on every io entry except on played instruments (the Instruments category group in schema/category-groups.yaml), whose single output jack has no panel position. Enforced by pnpm validate as E199, not by this schema."
           },
           "columnPosition": {
             "type": "number"
diff --git a/scripts/format-yaml.ts b/scripts/format-yaml.ts
index 2b4b50668..3039cac39 100644
--- a/scripts/format-yaml.ts
+++ b/scripts/format-yaml.ts
@@ -4,10 +4,15 @@
  * Moves `id` field to the top of each YAML file, then runs Prettier.
  * Replaces plain `prettier --write` for YAML formatting.
  *
- * Usage: tsx scripts/format-yaml.ts
+ * Usage:
+ *   tsx scripts/format-yaml.ts                      # whole catalog
+ *   tsx scripts/format-yaml.ts data/hardware/a.yaml # just these files
+ *
+ * Formatting has no cross-file dependency, so scoping it to the files an
+ * import touched turns a whole-catalog pass into an instant one.
  */
 
-import { execSync } from "node:child_process";
+import { execFileSync } from "node:child_process";
 import fs from "node:fs";
 import path from "node:path";
 import { parseDocument } from "yaml";
@@ -54,14 +59,46 @@ function moveIdToTop(filePath: string): boolean {
   return true;
 }
 
-let reordered = 0;
-
-for (const collection of COLLECTIONS) {
-  const files = getYamlFiles(path.join(DATA_DIR, collection));
-  for (const file of files) {
-    if (moveIdToTop(file)) {
-      reordered++;
+/**
+ * Files to format: the paths given on the command line, or every
+ * collection when none are. Formatting is per-file with no cross-file
+ * dependency, so scoping it to the handful of files an import touched
+ * turns a whole-catalog pass into an instant one.
+ */
+function filesToFormat(): { files: string[]; scoped: boolean } {
+  const args = process.argv.slice(2).filter((arg) => !arg.startsWith("-"));
+  if (args.length > 0) {
+    const resolved = args.map((arg) => path.resolve(process.cwd(), arg));
+    const missing = resolved.filter((file) => !fs.existsSync(file));
+    if (missing.length > 0) {
+      console.error(`No such file(s):\n${missing.map((f) => `  ${f}`).join("\n")}`);
+      process.exit(1);
+    }
+    // Only YAML: moveIdToTop parses every file it is handed, so a stray
+    // .md or .json argument would crash inside the YAML document parser
+    // rather than report anything useful. The unscoped path cannot hit
+    // this because getYamlFiles() already filters by extension.
+    const notYaml = resolved.filter((file) => !/\.ya?ml$/.test(file));
+    if (notYaml.length > 0) {
+      console.error(
+        `Not YAML (this script only formats .yaml/.yml):\n${notYaml.map((f) => `  ${f}`).join("\n")}`
+      );
+      process.exit(1);
     }
+    return { files: resolved, scoped: true };
+  }
+  return {
+    files: COLLECTIONS.flatMap((collection) => getYamlFiles(path.join(DATA_DIR, collection))),
+    scoped: false,
+  };
+}
+
+const { files, scoped } = filesToFormat();
+
+let reordered = 0;
+for (const file of files) {
+  if (moveIdToTop(file)) {
+    reordered++;
   }
 }
 
@@ -69,9 +106,14 @@ if (reordered > 0) {
   console.log(`Moved id to top in ${reordered} files`);
 }
 
-// Run Prettier on all YAML files
-console.log("Running Prettier...");
-execSync('prettier --write "data/**/*.yaml"', {
+console.log(scoped ? `Running Prettier on ${files.length} file(s)...` : "Running Prettier...");
+// Prettier is given explicit paths when scoped so it never walks the
+// whole data tree; the glob stays the default for a full run. These are
+// passed as argv rather than interpolated into a command string: the
+// scoped paths come from argv, and with no shell in between there is no
+// quoting to get wrong. Prettier expands the glob itself.
+const targets = scoped ? files.map((file) => path.relative(REPO_ROOT, file)) : ["data/**/*.yaml"];
+execFileSync("prettier", ["--write", ...targets], {
   cwd: REPO_ROOT,
   stdio: "inherit",
 });
diff --git a/scripts/generate-json-schemas.ts b/scripts/generate-json-schemas.ts
index f81da1795..e70f3f6f6 100644
--- a/scripts/generate-json-schemas.ts
+++ b/scripts/generate-json-schemas.ts
@@ -129,7 +129,17 @@ const ioSchema = {
     position: {
       type: "string",
       enum: ctx.ioPositions,
-      description: "Physical position on the device. Defined in schema/io-positions.yaml.",
+      // Not listed in `required`: the rule is conditional on the entry's
+      // primaryCategory, which JSON Schema cannot express here without
+      // duplicating the Instruments category group. `pnpm validate`
+      // enforces it (E199), so a file that omits position passes this
+      // schema and still fails validation — say so rather than let an
+      // editor or an external contributor read it as optional.
+      description:
+        "Physical position on the device. Defined in schema/io-positions.yaml. " +
+        "Required on every io entry except on played instruments (the Instruments " +
+        "category group in schema/category-groups.yaml), whose single output jack " +
+        "has no panel position. Enforced by pnpm validate as E199, not by this schema.",
     },
     columnPosition: { type: "number" },
     rowPosition: { type: "number" },
diff --git a/scripts/validate.ts b/scripts/validate.ts
index 4c1da6b5f..9d86b9820 100644
--- a/scripts/validate.ts
+++ b/scripts/validate.ts
@@ -1941,10 +1941,114 @@ function writeConsoleOutput(result: ValidationResult): void {
   console.log();
 }
 
+// =============================================================================
+// SCOPED VALIDATION (--files)
+// =============================================================================
+
+const COLLECTION_SCHEMAS: Record<string, z.ZodType> = {
+  manufacturers: ManufacturerSchema,
+  software: SoftwareSchema,
+  content: ContentSchema,
+  hardware: HardwareSchema,
+  accessories: AccessorySchema,
+};
+
+/**
+ * Validate only the named files, for the edit-fix loop during an import.
+ *
+ * This is a pre-flight, not a replacement for the full run. Per-file rules
+ * (schema shape, enums, io, name hygiene) are identical, and manufacturer
+ * references still resolve because manufacturer slugs come from filenames
+ * rather than file contents. What it cannot see is anything cross-file:
+ * duplicate IDs, supersedes targets, and supersedes cycles. The full
+ * `pnpm validate` still runs in the pre-commit hook and in CI, so nothing
+ * reaches main unchecked.
+ */
+function validateScoped(paths: string[]): number {
+  const allManufacturers = new Set(
+    getYamlFiles(path.join(DATA_DIR, "manufacturers")).map((file) =>
+      path.basename(file, path.extname(file))
+    )
+  );
+
+  const errors: ValidationError[] = [];
+  let checked = 0;
+
+  for (const given of paths) {
+    const file = path.resolve(process.cwd(), given);
+    if (!fs.existsSync(file)) {
+      console.error(`❌ No such file: ${given}`);
+      return 1;
+    }
+    // JSON is valid YAML, so without this a stray .json inside a collection
+    // directory would parse, validate and exit 0 — reporting success for a
+    // file the catalog never reads.
+    if (!/\.ya?ml$/.test(file)) {
+      console.error(`❌ Not YAML (this mode only validates .yaml/.yml): ${given}`);
+      return 1;
+    }
+    const collection = path.basename(path.dirname(file));
+    const schema = COLLECTION_SCHEMAS[collection];
+    if (!schema) {
+      console.error(
+        `❌ ${given} is not inside a known collection ` +
+          `(${Object.keys(COLLECTION_SCHEMAS).join(", ")}).`
+      );
+      return 1;
+    }
+    // No validSupersedesIds: the id set is a cross-file fact this mode
+    // deliberately does not build, and validateFile skips the check.
+    const error = validateFile(file, schema, allManufacturers);
+    if (error) errors.push(error);
+    checked += 1;
+  }
+
+  // Deliberately not writeConsoleOutput: its Stats block reports whole-catalog
+  // counts, which would read as an empty catalog here.
+  console.log(`\n📋 Scoped validation — ${checked} file(s)\n`);
+  console.log("─".repeat(70));
+  if (errors.length === 0) {
+    console.log("✅ No errors in the checked files.\n");
+  } else {
+    console.log("❌ Validation failed!\n");
+    for (const error of errors) {
+      console.log(`\n📄 ${error.file}`);
+      if (error.details && error.details.length > 0) {
+        for (const detail of error.details) {
+          const lineInfo = detail.line ? `:${detail.line}` : "";
+          console.log(`   ${detail.code ?? ""}${lineInfo}: ${detail.message}`);
+          console.log(`         Path: ${detail.path}`);
+          if (detail.docsUrl) console.log(`         Docs: ${detail.docsUrl}`);
+        }
+      } else {
+        for (const msg of error.errors) console.log(`   ⚠️  ${msg}`);
+      }
+    }
+    console.log();
+  }
+  console.log("─".repeat(70));
+  console.log(
+    "Cross-file checks (duplicate IDs, supersedes targets and cycles) are skipped.\n" +
+      "Run 'pnpm validate' before committing."
+  );
+  console.log();
+  return errors.length === 0 ? 0 : 1;
+}
+
 // =============================================================================
 // MAIN
 // =============================================================================
 
+const filesFlagIndex = process.argv.indexOf("--files");
+if (filesFlagIndex !== -1) {
+  const scopedPaths = process.argv.slice(filesFlagIndex + 1).filter((arg) => !arg.startsWith("-"));
+  if (scopedPaths.length === 0) {
+    console.error("❌ --files needs at least one path.");
+    process.exit(1);
+  }
+  process.exit(validateScoped(scopedPaths));
+}
+
 const result = validate();
 const idResult = validateIds();