diff --git a/apps/api/src/lib/recipe-translation.ts b/apps/api/src/lib/recipe-translation.ts
new file mode 100644
index 0000000..6eedfac
--- /dev/null
+++ b/apps/api/src/lib/recipe-translation.ts
@@ -0,0 +1,86 @@
+import type { ParsedRecipe, ParsedRecipeStep } from "./recipe-source-adapter.js";
+import {
+  type TechStepMappingRule,
+  loadTechStepMappingRules,
+  matchTechSteps,
+} from "./tech-step-matcher.js";
+
+/**
+ * The "Traduction en étapes" stage of the import pipeline described in
+ * specs/batch-cooking-architecture.md (Import depuis source → **Traduction
+ * en étapes** → Sauvegarde) — takes a source-agnostic {@link ParsedRecipe}
+ * (recipe-source-adapter.ts's `parse()` output) and declares each step's
+ * technique sequence, the same `techStepIds: number[]` shape
+ * `Step.techSteps`/`StepTechStep` (schema.prisma) will eventually persist.
+ *
+ * Deliberately doesn't touch ingredients — resolving free-text ingredient
+ * lines against our `Ingredient`/`Unit` catalogs is a separate, not-yet-built
+ * concern (see `ParsedRecipeIngredient`'s doc comment) — and doesn't turn
+ * the result into a saveable `Recipe` either (no `dietIds`/`visibility`/
+ * author, a source can't know those). This is one step of the pipeline, not
+ * the whole thing.
+ *
+ * `translateRecipeSteps` is pure (takes `techStepMappings` as a plain
+ * argument, same convention as `matchTechSteps` itself) so it's unit-testable
+ * without a database; `translateRecipe` is the DB-backed convenience wrapper
+ * a caller reaches for in practice, mirroring `tech-step-matcher.ts`'s own
+ * pure/DB-touching split.
+ */
+
+/** A {@link ParsedRecipeStep}, after tech-step detection — declares its technique sequence alongside the description/picture it already had. */
+export interface TranslatedRecipeStep extends ParsedRecipeStep {
+  /** Ordered sequence of detected `TechStep` ids (see `matchTechSteps`) — empty if this step doesn't mention any known technique. */
+  techStepIds: number[];
+}
+
+/** A {@link ParsedRecipe} whose `steps` have been translated — everything else (name, ingredients, portions, …) passes through unchanged. */
+export interface TranslatedRecipe extends Omit<ParsedRecipe, "steps"> {
+  steps: TranslatedRecipeStep[];
+}
+
+/**
+ * Declares each of `recipe`'s steps' technique sequence against
+ * `techStepMappings`, leaving everything else about the recipe untouched.
+ * Pure — testable with a hand-built mapping list, no database involved (see
+ * `translateRecipe` for the DB-backed loader). `techStepMappings` should
+ * already be filtered to the locale the caller cares about, same
+ * requirement `matchTechSteps` itself has.
+ */
+export function translateRecipeSteps(
+  recipe: ParsedRecipe,
+  techStepMappings: TechStepMappingRule[],
+): TranslatedRecipe {
+  return {
+    ...recipe,
+    steps: recipe.steps.map((step) => ({
+      ...step,
+      techStepIds: matchTechSteps(step.description, techStepMappings),
+    })),
+  };
+}
+
+/**
+ * Convenience wrapper around {@link translateRecipeSteps} that loads
+ * `locale`'s mapping catalog itself — what a caller reaches for when
+ * translating a single recipe on its own (e.g. the eventual "import this
+ * one recipe" endpoint). A caller translating many recipes at once should
+ * call `loadTechStepMappingRules` once and reuse it across
+ * `translateRecipeSteps` calls instead, the same "don't requery per item"
+ * reasoning `recipe.service.ts`'s `createRecipe`/`updateRecipe` already
+ * follow for manually-authored recipes.
+ *
+ * No user- or recipe-level language preference exists anywhere in the app
+ * yet (see `tech-step-matcher.ts`'s `loadTechStepMappingRules`) — callers
+ * pass a locale explicitly rather than this module guessing one. Note that
+ * an English-language source (e.g. TheMealDB) translated against `"fr"`
+ * mappings will currently get an empty `techStepIds` sequence on every
+ * step — matching-language mappings for that source's language don't exist
+ * yet, this stage doesn't invent them.
+ */
+export async function translateRecipe(
+  recipe: ParsedRecipe,
+  locale: string,
+): Promise<TranslatedRecipe> {
+  const techStepMappings = await loadTechStepMappingRules(locale);
+  return translateRecipeSteps(recipe, techStepMappings);
+}
diff --git a/apps/api/test/recipe-translation.test.ts b/apps/api/test/recipe-translation.test.ts
new file mode 100644
index 0000000..a984b2f
--- /dev/null
+++ b/apps/api/test/recipe-translation.test.ts
@@ -0,0 +1,143 @@
+import { expect } from "chai";
+import { prisma } from "../src/db/prisma.js";
+import type { ParsedRecipe } from "../src/lib/recipe-source-adapter.js";
+import { translateRecipe, translateRecipeSteps } from "../src/lib/recipe-translation.js";
+import type { TechStepMappingRule } from "../src/lib/tech-step-matcher.js";
+import { resetDatabase } from "../test-support/reset-db.js";
+
+/** A minimal fixture `ParsedRecipe` — only `steps` (built from `descriptions`) matters for most tests here, the rest is filler to prove it survives translation untouched. */
+function buildParsedRecipe(descriptions: string[]): ParsedRecipe {
+  return {
+    name: "Test Recipe",
+    description: "A recipe for testing",
+    picture: "https://example.test/recipe.jpg",
+    portions: 4,
+    sourceUrl: "https://example.test/recipes/1",
+    ingredients: [{ rawText: "1 egg", quantity: null, unit: null, name: "egg" }],
+    steps: descriptions.map((description, i) => ({
+      description,
+      picture: i === 0 ? "https://example.test/step1.jpg" : null,
+    })),
+  };
+}
+
+describe("recipe-translation", () => {
+  describe("translateRecipeSteps", () => {
+    const simmer: TechStepMappingRule = {
+      techStepId: 1,
+      expression: "\\bmijot(er|ez|e|ant|é)\\b",
+      weight: 15,
+    };
+    const preheat: TechStepMappingRule = {
+      techStepId: 2,
+      expression: "\\bpr[ée]chauff(er|ez|é|ée)\\b",
+      weight: 20,
+    };
+    const melt: TechStepMappingRule = {
+      techStepId: 3,
+      expression: "\\bfaire fondre\\b|\\bfaites fondre\\b",
+      weight: 15,
+    };
+
+    it("declares each step's technique sequence, preserving order", () => {
+      const recipe = buildParsedRecipe([
+        "Préchauffer la poêle, puis faire fondre le beurre",
+        "Servir immédiatement",
+        "Faire mijoter à feu doux",
+      ]);
+
+      const translated = translateRecipeSteps(recipe, [simmer, preheat, melt]);
+
+      expect(translated.steps.map((step) => step.techStepIds)).to.deep.equal([[2, 3], [], [1]]);
+    });
+
+    it("leaves description/picture untouched on each step", () => {
+      const recipe = buildParsedRecipe(["Faire mijoter à feu doux", "Servir"]);
+
+      const translated = translateRecipeSteps(recipe, [simmer]);
+
+      expect(translated.steps[0]).to.deep.equal({
+        description: "Faire mijoter à feu doux",
+        picture: "https://example.test/step1.jpg",
+        techStepIds: [1],
+      });
+      expect(translated.steps[1]).to.deep.equal({
+        description: "Servir",
+        picture: null,
+        techStepIds: [],
+      });
+    });
+
+    it("passes every other field through unchanged", () => {
+      const recipe = buildParsedRecipe(["Servir"]);
+
+      const translated = translateRecipeSteps(recipe, []);
+
+      expect(translated.name).to.equal(recipe.name);
+      expect(translated.description).to.equal(recipe.description);
+      expect(translated.picture).to.equal(recipe.picture);
+      expect(translated.portions).to.equal(recipe.portions);
+      expect(translated.sourceUrl).to.equal(recipe.sourceUrl);
+      expect(translated.ingredients).to.deep.equal(recipe.ingredients);
+    });
+
+    it("gives every step an empty sequence when there are no mappings at all", () => {
+      const recipe = buildParsedRecipe(["Faire mijoter à feu doux", "Préchauffer le four"]);
+
+      const translated = translateRecipeSteps(recipe, []);
+
+      expect(translated.steps.map((step) => step.techStepIds)).to.deep.equal([[], []]);
+    });
+
+    it("handles a recipe with no steps without error", () => {
+      const recipe = buildParsedRecipe([]);
+
+      const translated = translateRecipeSteps(recipe, [simmer]);
+
+      expect(translated.steps).to.deep.equal([]);
+    });
+  });
+
+  describe("translateRecipe", () => {
+    beforeEach(async () => {
+      await resetDatabase();
+    });
+
+    after(async () => {
+      await prisma.$disconnect();
+    });
+
+    it("resolves real TechStep ids from the seeded French catalog", async () => {
+      const simmer = await prisma.techStep.findFirstOrThrow({ where: { key: "simmer" } });
+      const chop = await prisma.techStep.findFirstOrThrow({ where: { key: "chop" } });
+      const recipe = buildParsedRecipe(["Hacher les oignons", "Faire mijoter à feu doux"]);
+
+      const translated = await translateRecipe(recipe, "fr");
+
+      expect(translated.steps.map((step) => step.techStepIds)).to.deep.equal([
+        [chop.id],
+        [simmer.id],
+      ]);
+    });
+
+    it("finds nothing for English text against the French catalog — the current locale gap", async () => {
+      // A step lifted verbatim from a real TheMealDB recipe.
+      const recipe = buildParsedRecipe([
+        "Bring a large saucepan of salted water to the boil",
+        "Chop the onions finely",
+      ]);
+
+      const translated = await translateRecipe(recipe, "fr");
+
+      expect(translated.steps.map((step) => step.techStepIds)).to.deep.equal([[], []]);
+    });
+
+    it("finds nothing for a locale with no mappings, even for text that would otherwise match", async () => {
+      const recipe = buildParsedRecipe(["Faire mijoter à feu doux"]);
+
+      const translated = await translateRecipe(recipe, "en");
+
+      expect(translated.steps.map((step) => step.techStepIds)).to.deep.equal([[]]);
+    });
+  });
+});