diff --git a/src/app/lib/selectPibiMeasures.ts b/src/app/lib/selectPibiMeasures.ts
new file mode 100644
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+++ b/src/app/lib/selectPibiMeasures.ts
@@ -0,0 +1,187 @@
+/**
+ * PIBI-selection service (issue #254)
+ *
+ * Lets an approver mark which measures on a deal are going for PIBI. The
+ * selection is recorded locally as `user_defined_deal_measures` rows with
+ * `source = "pibi_ordered"` and pushed back to HubSpot under the
+ * `measures_for_pibi_ordered` deal property via `syncMeasuresFieldToHubSpot`.
+ *
+ * Semantics deliberately mirror instruct-measure (issue #253):
+ *  - The incoming `measureNames[]` is the NEW desired set, not a delta. The
+ *    service REPLACES all existing `pibi_ordered` rows for the deal, then
+ *    re-inserts one row per selected measure.
+ *  - No `deal_measure_approvals` rows are created or modified.
+ *  - `pushed_at` is stamped on every new row when HubSpot sync succeeds;
+ *    left null on failure so a reconcile job can retry.
+ *  - HubSpot push failures do NOT roll back the DB.
+ *
+ * The service accepts injectable deps so it stays environment-free in tests.
+ */
+import { and, eq } from "drizzle-orm";
+import { db } from "@/app/db/db";
+import { userDefinedDealMeasures } from "@/app/db/schema/user_defined_deal_measures";
+import { syncMeasuresFieldToHubSpot as defaultSyncMeasuresField } from "@/app/lib/hubspot/dealSync";
+
+export const PIBI_MEASURES_PROP = "measures_for_pibi_ordered";
+
+// ---------------------------------------------------------------------------
+// Injected dependency types — mirrors the pattern in instructMeasure.ts so
+// the service is fully testable without touching the real DB or HubSpot.
+// ---------------------------------------------------------------------------
+
+export type SyncMeasuresField = typeof defaultSyncMeasuresField;
+
+/**
+ * Replace the pibi_ordered rows for the deal inside a transaction.
+ * Returns the IDs of the newly inserted rows (one per selected measure).
+ */
+export type RunPibiTx = (params: {
+  dealId: string;
+  measureNames: string[];
+  userId: bigint;
+}) => Promise<{ insertedRowIds: bigint[] }>;
+
+export type StampPushedAt = (rowIds: bigint[]) => Promise<void>;
+
+// ---------------------------------------------------------------------------
+// Public result type
+// ---------------------------------------------------------------------------
+
+export type SelectPibiMeasuresResult =
+  | {
+      ok: true;
+      insertedRowIds: bigint[];
+      hubspotSync: "ok" | "failed";
+      hubspotError?: string;
+    }
+  | { ok: false; error: string };
+
+// ---------------------------------------------------------------------------
+// Input
+// ---------------------------------------------------------------------------
+
+export interface SelectPibiMeasuresInput {
+  dealId: string;
+  /** The FULL desired set of PIBI measures (replaces any prior selection). */
+  measureNames: string[];
+  userId: bigint;
+  deps?: {
+    runPibiTx?: RunPibiTx;
+    syncMeasuresField?: SyncMeasuresField;
+    stampPushedAt?: StampPushedAt;
+  };
+}
+
+// ---------------------------------------------------------------------------
+// Default DB-backed implementations
+// ---------------------------------------------------------------------------
+
+const defaultRunPibiTx: RunPibiTx = async ({ dealId, measureNames, userId }) => {
+  return await db.transaction(async (tx) => {
+    // Delete ALL existing pibi_ordered rows for this deal so the new
+    // selection fully replaces the previous one.
+    await tx
+      .delete(userDefinedDealMeasures)
+      .where(
+        and(
+          eq(userDefinedDealMeasures.hubspotDealId, dealId),
+          eq(userDefinedDealMeasures.source, "pibi_ordered"),
+        ),
+      );
+
+    if (measureNames.length === 0) {
+      return { insertedRowIds: [] };
+    }
+
+    const inserted = await tx
+      .insert(userDefinedDealMeasures)
+      .values(
+        measureNames.map((measureName) => ({
+          hubspotDealId: dealId,
+          measureName,
+          source: "pibi_ordered" as const,
+          createdByUserId: userId,
+        })),
+      )
+      .returning({ id: userDefinedDealMeasures.id });
+
+    return { insertedRowIds: inserted.map((r) => r.id) };
+  });
+};
+
+const defaultStampPushedAt: StampPushedAt = async (rowIds) => {
+  if (rowIds.length === 0) return;
+  for (const rowId of rowIds) {
+    await db
+      .update(userDefinedDealMeasures)
+      .set({ pushedAt: new Date() })
+      .where(eq(userDefinedDealMeasures.id, rowId));
+  }
+};
+
+// ---------------------------------------------------------------------------
+// Service entry-point
+// ---------------------------------------------------------------------------
+
+export async function selectPibiMeasures(
+  input: SelectPibiMeasuresInput,
+): Promise<SelectPibiMeasuresResult> {
+  const runPibiTx = input.deps?.runPibiTx ?? defaultRunPibiTx;
+  const syncMeasuresField =
+    input.deps?.syncMeasuresField ?? defaultSyncMeasuresField;
+  const stampPushedAt = input.deps?.stampPushedAt ?? defaultStampPushedAt;
+
+  // -------------------------------------------------------------------------
+  // DB transaction. Any throw here rolls everything back — no row is
+  // touched, no HubSpot push happens.
+  // -------------------------------------------------------------------------
+  let txResult: { insertedRowIds: bigint[] };
+  try {
+    txResult = await runPibiTx({
+      dealId: input.dealId,
+      measureNames: input.measureNames,
+      userId: input.userId,
+    });
+  } catch (err) {
+    const message =
+      err instanceof Error ? err.message : "Failed to save PIBI measures";
+    console.error("[selectPibiMeasures] transaction failed", {
+      dealId: input.dealId,
+      error: err,
+    });
+    return { ok: false, error: message };
+  }
+
+  // -------------------------------------------------------------------------
+  // Post-commit: push the new selection list to HubSpot. Failures here do
+  // NOT roll back the DB; `pushed_at` simply stays null.
+  // -------------------------------------------------------------------------
+  const syncResult = await syncMeasuresField({
+    hubspotDealId: input.dealId,
+    propName: PIBI_MEASURES_PROP,
+    measureNames: input.measureNames,
+  });
+
+  if (syncResult.ok) {
+    try {
+      await stampPushedAt(txResult.insertedRowIds);
+    } catch (err) {
+      console.error("[selectPibiMeasures] failed to stamp pushed_at", {
+        rowIds: txResult.insertedRowIds.map(String),
+        error: err,
+      });
+    }
+    return {
+      ok: true,
+      insertedRowIds: txResult.insertedRowIds,
+      hubspotSync: "ok",
+    };
+  }
+
+  return {
+    ok: true,
+    insertedRowIds: txResult.insertedRowIds,
+    hubspotSync: "failed",
+    hubspotError: syncResult.error,
+  };
+}