diff --git a/scripts/dev-recommender-smoke.ts b/scripts/dev-recommender-smoke.ts
new file mode 100644
index 0000000..b0b3584
--- /dev/null
+++ b/scripts/dev-recommender-smoke.ts
@@ -0,0 +1,52 @@
+/**
+ * Dev-only smoke check for the berth recommender. Resolves the first
+ * port-nimara interest (with desired dims set) and prints the top-N
+ * recommendations.
+ *
+ *   pnpm tsx scripts/dev-recommender-smoke.ts
+ */
+import 'dotenv/config';
+import { eq, isNotNull, and } from 'drizzle-orm';
+
+import { db } from '@/lib/db';
+import { ports } from '@/lib/db/schema/ports';
+import { interests } from '@/lib/db/schema/interests';
+import { recommendBerths } from '@/lib/services/berth-recommender.service';
+
+async function main() {
+  const [port] = await db
+    .select({ id: ports.id })
+    .from(ports)
+    .where(eq(ports.slug, 'port-nimara'))
+    .limit(1);
+  if (!port) throw new Error('port-nimara not found');
+
+  const [interest] = await db
+    .select({ id: interests.id })
+    .from(interests)
+    .where(and(eq(interests.portId, port.id), isNotNull(interests.desiredLengthFt)))
+    .limit(1);
+  if (!interest) throw new Error('No interest with desired dims set');
+
+  console.log(`> Recommending berths for interest ${interest.id} on port ${port.id}…`);
+  const recs = await recommendBerths({
+    interestId: interest.id,
+    portId: port.id,
+  });
+
+  console.log(`> ${recs.length} recommendations:`);
+  for (const r of recs) {
+    console.log(
+      `  ${r.mooringNumber.padEnd(5)} tier=${r.tier} fit=${r.fitScore}  ` +
+        `${r.lengthFt}×${r.widthFt}×${r.draftFt} ft  buf=${r.sizeBufferPct}%  ` +
+        `${r.reasons.dimensional}; ${r.reasons.pipeline}`,
+    );
+  }
+}
+
+main()
+  .then(() => process.exit(0))
+  .catch((err) => {
+    console.error(err);
+    process.exit(1);
+  });
diff --git a/src/lib/services/berth-recommender.service.ts b/src/lib/services/berth-recommender.service.ts
new file mode 100644
index 0000000..c2fb21a
--- /dev/null
+++ b/src/lib/services/berth-recommender.service.ts
@@ -0,0 +1,631 @@
+/**
+ * Berth recommender (plan §4.4 + §13).
+ *
+ * Pure SQL ranking - no AI. The single CTE chain:
+ *
+ *   1. interest_input  - the desired dimensions + port for this interest
+ *   2. feasible        - berths in the port that can fit the yacht
+ *                        (length/width/draft >= desired) AND don't exceed
+ *                        the configured max-oversize percentage
+ *   3. tier_inputs     - per-berth aggregates over interest_berths +
+ *                        interests: active count, lost count, max stage
+ *                        among active interests, latest fall-through
+ *                        timestamp, total historical interest count,
+ *                        EOI-signed count
+ *   4. classified      - assign tier A/B/C/D
+ *
+ * The feasible berths are returned to JavaScript for fit-score + heat
+ * calculation - keeping that out of SQL lets per-port admins tune the
+ * heat weights without a code deploy.
+ *
+ * Heat scoring (only relevant for tier B; berths surface back into the
+ * recommender pool after a fall-through):
+ *   - recency             : how recently did the last interest fall through
+ *   - furthest stage       : how close did the prior interest get to closing
+ *   - historical interest  : how often does this berth attract interest
+ *   - historical EOI count : how often does interest convert to EOI
+ *
+ * Per-port settings (defaults below) drive the cap, fall-through policy,
+ * heat weights, and tier-D visibility.
+ */
+
+import { and, eq, inArray, sql } from 'drizzle-orm';
+
+import { db } from '@/lib/db';
+import { systemSettings } from '@/lib/db/schema/system';
+import { interests } from '@/lib/db/schema/interests';
+
+// ─── Settings ──────────────────────────────────────────────────────────────
+
+export interface RecommenderSettings {
+  maxOversizePct: number;
+  topNDefault: number;
+  fallthroughPolicy: 'immediate_with_heat' | 'cooldown' | 'never_auto_recommend';
+  fallthroughCooldownDays: number;
+  heatWeightRecency: number;
+  heatWeightFurthestStage: number;
+  heatWeightInterestCount: number;
+  heatWeightEoiCount: number;
+  tierLadderHideLateStage: boolean;
+}
+
+export const DEFAULT_RECOMMENDER_SETTINGS: RecommenderSettings = {
+  maxOversizePct: 30,
+  topNDefault: 8,
+  fallthroughPolicy: 'immediate_with_heat',
+  fallthroughCooldownDays: 30,
+  heatWeightRecency: 30,
+  heatWeightFurthestStage: 40,
+  heatWeightInterestCount: 15,
+  heatWeightEoiCount: 15,
+  tierLadderHideLateStage: true,
+};
+
+const SETTINGS_KEYS = {
+  maxOversizePct: 'recommender_max_oversize_pct',
+  topNDefault: 'recommender_top_n_default',
+  fallthroughPolicy: 'fallthrough_policy',
+  fallthroughCooldownDays: 'fallthrough_cooldown_days',
+  heatWeightRecency: 'heat_weight_recency',
+  heatWeightFurthestStage: 'heat_weight_furthest_stage',
+  heatWeightInterestCount: 'heat_weight_interest_count',
+  heatWeightEoiCount: 'heat_weight_eoi_count',
+  tierLadderHideLateStage: 'tier_ladder_hide_late_stage',
+} as const;
+
+/**
+ * Reads recommender settings for the port, layered over the defaults.
+ * Per-port row wins; null portId row is the global fallback; defaults
+ * cover anything still missing.
+ */
+export async function loadRecommenderSettings(portId: string): Promise<RecommenderSettings> {
+  const rows = await db
+    .select({ key: systemSettings.key, value: systemSettings.value, portId: systemSettings.portId })
+    .from(systemSettings)
+    .where(
+      and(
+        inArray(systemSettings.key, Object.values(SETTINGS_KEYS)),
+        sql`(${systemSettings.portId} = ${portId} OR ${systemSettings.portId} IS NULL)`,
+      ),
+    );
+
+  const portRows = new Map<string, unknown>();
+  const globalRows = new Map<string, unknown>();
+  for (const r of rows) {
+    if (r.portId === portId) portRows.set(r.key, r.value);
+    else if (r.portId === null) globalRows.set(r.key, r.value);
+  }
+
+  const pick = <T>(key: string, parse: (v: unknown) => T | null, fallback: T): T => {
+    const portVal = portRows.has(key) ? parse(portRows.get(key)) : null;
+    if (portVal !== null) return portVal;
+    const globalVal = globalRows.has(key) ? parse(globalRows.get(key)) : null;
+    if (globalVal !== null) return globalVal;
+    return fallback;
+  };
+
+  const asNumber = (v: unknown): number | null => {
+    if (v === null || v === undefined) return null;
+    if (typeof v === 'number') return Number.isFinite(v) ? v : null;
+    if (typeof v === 'string') {
+      const n = parseFloat(v);
+      return Number.isFinite(n) ? n : null;
+    }
+    return null;
+  };
+  const asBool = (v: unknown): boolean | null => (typeof v === 'boolean' ? v : null);
+  const asPolicy = (v: unknown): RecommenderSettings['fallthroughPolicy'] | null => {
+    if (v === 'immediate_with_heat' || v === 'cooldown' || v === 'never_auto_recommend') {
+      return v;
+    }
+    return null;
+  };
+
+  return {
+    maxOversizePct: pick(
+      SETTINGS_KEYS.maxOversizePct,
+      asNumber,
+      DEFAULT_RECOMMENDER_SETTINGS.maxOversizePct,
+    ),
+    topNDefault: pick(
+      SETTINGS_KEYS.topNDefault,
+      asNumber,
+      DEFAULT_RECOMMENDER_SETTINGS.topNDefault,
+    ),
+    fallthroughPolicy: pick(
+      SETTINGS_KEYS.fallthroughPolicy,
+      asPolicy,
+      DEFAULT_RECOMMENDER_SETTINGS.fallthroughPolicy,
+    ),
+    fallthroughCooldownDays: pick(
+      SETTINGS_KEYS.fallthroughCooldownDays,
+      asNumber,
+      DEFAULT_RECOMMENDER_SETTINGS.fallthroughCooldownDays,
+    ),
+    heatWeightRecency: pick(
+      SETTINGS_KEYS.heatWeightRecency,
+      asNumber,
+      DEFAULT_RECOMMENDER_SETTINGS.heatWeightRecency,
+    ),
+    heatWeightFurthestStage: pick(
+      SETTINGS_KEYS.heatWeightFurthestStage,
+      asNumber,
+      DEFAULT_RECOMMENDER_SETTINGS.heatWeightFurthestStage,
+    ),
+    heatWeightInterestCount: pick(
+      SETTINGS_KEYS.heatWeightInterestCount,
+      asNumber,
+      DEFAULT_RECOMMENDER_SETTINGS.heatWeightInterestCount,
+    ),
+    heatWeightEoiCount: pick(
+      SETTINGS_KEYS.heatWeightEoiCount,
+      asNumber,
+      DEFAULT_RECOMMENDER_SETTINGS.heatWeightEoiCount,
+    ),
+    tierLadderHideLateStage: pick(
+      SETTINGS_KEYS.tierLadderHideLateStage,
+      asBool,
+      DEFAULT_RECOMMENDER_SETTINGS.tierLadderHideLateStage,
+    ),
+  };
+}
+
+// ─── Tier mapping ──────────────────────────────────────────────────────────
+
+const STAGE_ORDER: Record<string, number> = {
+  open: 1,
+  details_sent: 2,
+  in_communication: 3,
+  eoi_sent: 4,
+  eoi_signed: 5,
+  deposit_10pct: 6,
+  contract_sent: 7,
+  contract_signed: 8,
+  completed: 9,
+};
+
+/** Stage at which a berth is "in late stage" (Tier D when active). */
+const LATE_STAGE_THRESHOLD = STAGE_ORDER.deposit_10pct!; // 6
+
+export type Tier = 'A' | 'B' | 'C' | 'D';
+
+interface TierInputs {
+  activeInterestCount: number;
+  lostCount: number;
+  maxActiveStage: number;
+}
+
+export function classifyTier(t: TierInputs): Tier {
+  if (t.activeInterestCount > 0 && t.maxActiveStage >= LATE_STAGE_THRESHOLD) return 'D';
+  if (t.activeInterestCount > 0) return 'C';
+  if (t.lostCount > 0) return 'B';
+  return 'A';
+}
+
+// ─── Heat scoring ──────────────────────────────────────────────────────────
+
+interface HeatInputs {
+  latestFallthroughAt: Date | null;
+  totalInterestCount: number;
+  eoiSignedCount: number;
+  /** Stage code at the time of the most recent fall-through. */
+  fallthroughMaxStage: number;
+}
+
+export interface HeatBreakdown {
+  recency: number;
+  furthestStage: number;
+  interestCount: number;
+  eoiCount: number;
+  total: number;
+}
+
+/**
+ * 0..100 heat score with per-port-tunable weights. Each component is
+ * normalized 0..1 before being multiplied by its weight; the totals sum
+ * to 100 by construction (the four weights are expected to sum to 100,
+ * but the function clamps regardless so admin-tuning errors don't
+ * produce out-of-range scores).
+ */
+export function computeHeat(
+  inputs: HeatInputs,
+  weights: Pick<
+    RecommenderSettings,
+    | 'heatWeightRecency'
+    | 'heatWeightFurthestStage'
+    | 'heatWeightInterestCount'
+    | 'heatWeightEoiCount'
+  >,
+  now: Date = new Date(),
+): HeatBreakdown {
+  const weightSum =
+    weights.heatWeightRecency +
+    weights.heatWeightFurthestStage +
+    weights.heatWeightInterestCount +
+    weights.heatWeightEoiCount;
+  const norm = weightSum > 0 ? 100 / weightSum : 0;
+
+  // 1.0 if fallthrough <= 30 days, decays linearly to 0 at 365 days.
+  let recency = 0;
+  if (inputs.latestFallthroughAt) {
+    const ageDays = (now.getTime() - inputs.latestFallthroughAt.getTime()) / 86_400_000;
+    if (ageDays <= 30) recency = 1;
+    else if (ageDays >= 365) recency = 0;
+    else recency = 1 - (ageDays - 30) / (365 - 30);
+  }
+
+  // 0 if max stage is open; 1 at signed/deposit/contract.
+  const furthestStage =
+    inputs.fallthroughMaxStage <= 1
+      ? 0
+      : Math.min(1, (inputs.fallthroughMaxStage - 1) / (LATE_STAGE_THRESHOLD - 1));
+
+  // 0 at 0 interests, 1 at 5+ interests.
+  const interestCount = Math.min(1, inputs.totalInterestCount / 5);
+
+  // 0 at 0 EOIs, 1 at 3+ EOIs.
+  const eoiCount = Math.min(1, inputs.eoiSignedCount / 3);
+
+  const r = recency * weights.heatWeightRecency * norm;
+  const f = furthestStage * weights.heatWeightFurthestStage * norm;
+  const ic = interestCount * weights.heatWeightInterestCount * norm;
+  const ec = eoiCount * weights.heatWeightEoiCount * norm;
+  const total = Math.max(0, Math.min(100, r + f + ic + ec));
+
+  return {
+    recency: Math.round(r * 100) / 100,
+    furthestStage: Math.round(f * 100) / 100,
+    interestCount: Math.round(ic * 100) / 100,
+    eoiCount: Math.round(ec * 100) / 100,
+    total: Math.round(total * 100) / 100,
+  };
+}
+
+// ─── Recommend ────────────────────────────────────────────────────────────
+
+export interface RecommendBerthsArgs {
+  interestId: string;
+  portId: string;
+  /** Override the per-port topNDefault. */
+  topN?: number;
+  /** Override the per-port maxOversizePct. */
+  maxOversizePct?: number;
+  /** Show late-stage (Tier D) berths even when the per-port setting hides them. */
+  showLateStage?: boolean;
+  /** Optional rep-supplied amenity filters. */
+  amenityFilters?: {
+    minPowerCapacityKw?: number;
+    requiredVoltage?: number;
+    requiredAccess?: string;
+    requiredMooringType?: string;
+    requiredCleatCapacity?: string;
+  };
+}
+
+export interface Recommendation {
+  berthId: string;
+  mooringNumber: string;
+  area: string | null;
+  tier: Tier;
+  fitScore: number;
+  sizeBufferPct: number | null;
+  heat: HeatBreakdown | null;
+  reasons: {
+    dimensional: string;
+    pipeline: string;
+    amenities?: string;
+    heat?: string;
+  };
+  lengthFt: number | null;
+  widthFt: number | null;
+  draftFt: number | null;
+  status: string;
+  amenities: {
+    powerCapacity: number | null;
+    voltage: number | null;
+    access: string | null;
+    mooringType: string | null;
+    cleatCapacity: string | null;
+  };
+}
+
+interface RawRow extends Record<string, unknown> {
+  berthId: string;
+  mooringNumber: string;
+  area: string | null;
+  status: string;
+  lengthFt: string | null;
+  widthFt: string | null;
+  draftFt: string | null;
+  powerCapacity: string | null;
+  voltage: string | null;
+  access: string | null;
+  mooringType: string | null;
+  cleatCapacity: string | null;
+  activeInterestCount: number;
+  lostCount: number;
+  maxActiveStage: number;
+  latestFallthroughAt: Date | null;
+  fallthroughMaxStage: number;
+  totalInterestCount: number;
+  eoiSignedCount: number;
+}
+
+interface InterestInput {
+  desiredLengthFt: number | null;
+  desiredWidthFt: number | null;
+  desiredDraftFt: number | null;
+  portId: string;
+}
+
+async function loadInterestInput(interestId: string): Promise<InterestInput | null> {
+  const [row] = await db
+    .select({
+      desiredLengthFt: interests.desiredLengthFt,
+      desiredWidthFt: interests.desiredWidthFt,
+      desiredDraftFt: interests.desiredDraftFt,
+      portId: interests.portId,
+    })
+    .from(interests)
+    .where(eq(interests.id, interestId))
+    .limit(1);
+  if (!row) return null;
+  const toNum = (v: string | null): number | null => {
+    if (v === null) return null;
+    const n = parseFloat(v);
+    return Number.isFinite(n) ? n : null;
+  };
+  return {
+    desiredLengthFt: toNum(row.desiredLengthFt),
+    desiredWidthFt: toNum(row.desiredWidthFt),
+    desiredDraftFt: toNum(row.desiredDraftFt),
+    portId: row.portId,
+  };
+}
+
+/**
+ * Run the recommender. Returns ranked recommendations top-N. Multi-port
+ * isolation is enforced both in the CTE (`b.port_id = $portId`) and via
+ * the interest's own port_id - cross-port queries fail explicitly
+ * rather than leak (§14.10 critical).
+ */
+export async function recommendBerths(args: RecommendBerthsArgs): Promise<Recommendation[]> {
+  const settings = await loadRecommenderSettings(args.portId);
+  const interestInput = await loadInterestInput(args.interestId);
+  if (!interestInput) return [];
+  if (interestInput.portId !== args.portId) {
+    // Defensive: caller passed a port that doesn't own this interest.
+    throw new Error(
+      `Recommender: interest ${args.interestId} belongs to port ${interestInput.portId}, not ${args.portId}`,
+    );
+  }
+
+  const oversizePct = args.maxOversizePct ?? settings.maxOversizePct;
+  const topN = args.topN ?? settings.topNDefault;
+  const showLateStage = args.showLateStage ?? !settings.tierLadderHideLateStage;
+
+  const oversizeMultiplier = 1 + oversizePct / 100;
+
+  const predicates: ReturnType<typeof sql>[] = [
+    sql`b.port_id = ${args.portId}`,
+    sql`b.status <> 'sold'`,
+  ];
+  if (interestInput.desiredLengthFt !== null) {
+    predicates.push(sql`b.length_ft::numeric >= ${interestInput.desiredLengthFt}`);
+    predicates.push(
+      sql`b.length_ft::numeric <= ${interestInput.desiredLengthFt}::numeric * ${oversizeMultiplier}::numeric`,
+    );
+  }
+  if (interestInput.desiredWidthFt !== null) {
+    predicates.push(sql`b.width_ft::numeric >= ${interestInput.desiredWidthFt}`);
+  }
+  if (interestInput.desiredDraftFt !== null) {
+    predicates.push(sql`b.draft_ft::numeric >= ${interestInput.desiredDraftFt}`);
+  }
+  if (args.amenityFilters?.minPowerCapacityKw != null) {
+    predicates.push(sql`b.power_capacity::numeric >= ${args.amenityFilters.minPowerCapacityKw}`);
+  }
+  if (args.amenityFilters?.requiredVoltage != null) {
+    predicates.push(sql`b.voltage::numeric = ${args.amenityFilters.requiredVoltage}`);
+  }
+  if (args.amenityFilters?.requiredAccess) {
+    predicates.push(sql`b.access = ${args.amenityFilters.requiredAccess}`);
+  }
+  if (args.amenityFilters?.requiredMooringType) {
+    predicates.push(sql`b.mooring_type = ${args.amenityFilters.requiredMooringType}`);
+  }
+  if (args.amenityFilters?.requiredCleatCapacity) {
+    predicates.push(sql`b.cleat_capacity = ${args.amenityFilters.requiredCleatCapacity}`);
+  }
+  const whereClause = sql.join(predicates, sql` AND `);
+
+  const rawRows = await db.execute<RawRow>(sql`
+    WITH feasible AS (
+      SELECT b.*
+      FROM berths b
+      WHERE ${whereClause}
+    ),
+    aggregates AS (
+      SELECT
+        f.id AS berth_id,
+        COUNT(*) FILTER (WHERE i.archived_at IS NULL AND i.outcome IS NULL) AS active_interest_count,
+        COUNT(*) FILTER (
+          WHERE i.outcome IS NOT NULL AND i.outcome::text LIKE 'lost%'
+        ) AS lost_count,
+        COALESCE(
+          MAX(CASE i.pipeline_stage
+            WHEN 'open' THEN 1
+            WHEN 'details_sent' THEN 2
+            WHEN 'in_communication' THEN 3
+            WHEN 'eoi_sent' THEN 4
+            WHEN 'eoi_signed' THEN 5
+            WHEN 'deposit_10pct' THEN 6
+            WHEN 'contract_sent' THEN 7
+            WHEN 'contract_signed' THEN 8
+            ELSE 0 END
+          ) FILTER (WHERE i.archived_at IS NULL AND i.outcome IS NULL),
+          0
+        ) AS max_active_stage,
+        MAX(i.outcome_at) FILTER (
+          WHERE i.outcome IS NOT NULL AND i.outcome::text LIKE 'lost%'
+        ) AS latest_fallthrough_at,
+        COALESCE(
+          MAX(CASE i.pipeline_stage
+            WHEN 'open' THEN 1
+            WHEN 'details_sent' THEN 2
+            WHEN 'in_communication' THEN 3
+            WHEN 'eoi_sent' THEN 4
+            WHEN 'eoi_signed' THEN 5
+            WHEN 'deposit_10pct' THEN 6
+            WHEN 'contract_sent' THEN 7
+            WHEN 'contract_signed' THEN 8
+            ELSE 0 END
+          ) FILTER (WHERE i.outcome IS NOT NULL AND i.outcome::text LIKE 'lost%'),
+          0
+        ) AS fallthrough_max_stage,
+        COUNT(*) AS total_interest_count,
+        COUNT(*) FILTER (WHERE i.eoi_status = 'signed') AS eoi_signed_count
+      FROM feasible f
+      LEFT JOIN interest_berths ib ON ib.berth_id = f.id
+      LEFT JOIN interests i ON i.id = ib.interest_id
+      GROUP BY f.id
+    )
+    SELECT
+      f.id AS "berthId",
+      f.mooring_number AS "mooringNumber",
+      f.area,
+      f.status,
+      f.length_ft AS "lengthFt",
+      f.width_ft AS "widthFt",
+      f.draft_ft AS "draftFt",
+      f.power_capacity AS "powerCapacity",
+      f.voltage,
+      f.access,
+      f.mooring_type AS "mooringType",
+      f.cleat_capacity AS "cleatCapacity",
+      a.active_interest_count::int AS "activeInterestCount",
+      a.lost_count::int AS "lostCount",
+      a.max_active_stage::int AS "maxActiveStage",
+      a.latest_fallthrough_at AS "latestFallthroughAt",
+      a.fallthrough_max_stage::int AS "fallthroughMaxStage",
+      a.total_interest_count::int AS "totalInterestCount",
+      a.eoi_signed_count::int AS "eoiSignedCount"
+    FROM feasible f
+    JOIN aggregates a ON a.berth_id = f.id
+  `);
+
+  const rows = (rawRows as { rows?: RawRow[] }).rows ?? (rawRows as unknown as RawRow[]);
+
+  // Apply tier classification + fall-through cooldown filter + heat scoring + fit ranking in JS.
+  const cooldownCutoff =
+    settings.fallthroughPolicy === 'cooldown'
+      ? new Date(Date.now() - settings.fallthroughCooldownDays * 86_400_000)
+      : null;
+
+  const recommendations: Recommendation[] = [];
+  for (const r of rows) {
+    const tier = classifyTier(r);
+    if (tier === 'D' && !showLateStage) continue;
+
+    if (tier === 'B' && settings.fallthroughPolicy === 'never_auto_recommend') continue;
+    if (
+      tier === 'B' &&
+      cooldownCutoff &&
+      r.latestFallthroughAt &&
+      new Date(r.latestFallthroughAt) > cooldownCutoff
+    ) {
+      continue;
+    }
+
+    const lengthFt = r.lengthFt === null ? null : parseFloat(r.lengthFt);
+    const widthFt = r.widthFt === null ? null : parseFloat(r.widthFt);
+    const draftFt = r.draftFt === null ? null : parseFloat(r.draftFt);
+
+    const sizeBufferPct =
+      interestInput.desiredLengthFt && lengthFt
+        ? Math.round(
+            ((lengthFt - interestInput.desiredLengthFt) / interestInput.desiredLengthFt) * 1000,
+          ) / 10
+        : null;
+
+    const heat =
+      tier === 'B'
+        ? computeHeat(
+            {
+              latestFallthroughAt: r.latestFallthroughAt ? new Date(r.latestFallthroughAt) : null,
+              totalInterestCount: r.totalInterestCount,
+              eoiSignedCount: r.eoiSignedCount,
+              fallthroughMaxStage: r.fallthroughMaxStage,
+            },
+            settings,
+          )
+        : null;
+
+    // Fit score: tier weight + 1/(1+buffer) closeness + heat boost.
+    // Tier base scores: A=80, B=60+heat, C=40, D=20. Smaller buffer adds up to 20.
+    const tierBase = { A: 80, B: 60, C: 40, D: 20 }[tier];
+    const closeness =
+      sizeBufferPct === null
+        ? 10
+        : Math.max(0, 20 - Math.abs(sizeBufferPct) / Math.max(1, oversizePct / 20));
+    const heatBoost = heat ? heat.total / 5 : 0;
+    const fitScore = Math.max(0, Math.min(100, tierBase + closeness + heatBoost));
+
+    recommendations.push({
+      berthId: r.berthId,
+      mooringNumber: r.mooringNumber,
+      area: r.area,
+      tier,
+      fitScore: Math.round(fitScore * 10) / 10,
+      sizeBufferPct,
+      heat,
+      reasons: {
+        dimensional:
+          sizeBufferPct === null
+            ? 'No length specified - all feasible berths shown'
+            : `Within ${Math.abs(sizeBufferPct)}% of desired length`,
+        pipeline: pipelineReason(tier, r),
+        ...(heat ? { heat: heatSummary(heat) } : {}),
+        ...(args.amenityFilters && Object.keys(args.amenityFilters).length > 0
+          ? { amenities: 'All required amenities matched' }
+          : {}),
+      },
+      lengthFt,
+      widthFt,
+      draftFt,
+      status: r.status,
+      amenities: {
+        powerCapacity: r.powerCapacity === null ? null : parseFloat(r.powerCapacity),
+        voltage: r.voltage === null ? null : parseFloat(r.voltage),
+        access: r.access,
+        mooringType: r.mooringType,
+        cleatCapacity: r.cleatCapacity,
+      },
+    });
+  }
+
+  recommendations.sort((a, b) => {
+    const tierRank = (t: Tier): number => ({ A: 1, B: 2, C: 3, D: 4 })[t];
+    if (tierRank(a.tier) !== tierRank(b.tier)) return tierRank(a.tier) - tierRank(b.tier);
+    return b.fitScore - a.fitScore;
+  });
+
+  return recommendations.slice(0, topN);
+}
+
+function pipelineReason(tier: Tier, r: RawRow): string {
+  switch (tier) {
+    case 'A':
+      return 'No prior interest history';
+    case 'B':
+      return `Previously fell through (${r.lostCount} time${r.lostCount === 1 ? '' : 's'})`;
+    case 'C':
+      return `${r.activeInterestCount} active interest${r.activeInterestCount === 1 ? '' : 's'} in early stage`;
+    case 'D':
+      return 'Active interest in late stage';
+  }
+}
+
+function heatSummary(h: HeatBreakdown): string {
+  return `Heat ${h.total.toFixed(0)}/100 (recency ${h.recency.toFixed(0)}, stage ${h.furthestStage.toFixed(0)}, count ${h.interestCount.toFixed(0)}, EOI ${h.eoiCount.toFixed(0)})`;
+}
diff --git a/tests/unit/services/berth-recommender.test.ts b/tests/unit/services/berth-recommender.test.ts
new file mode 100644
index 0000000..5091b2a
--- /dev/null
+++ b/tests/unit/services/berth-recommender.test.ts
@@ -0,0 +1,186 @@
+import { describe, it, expect } from 'vitest';
+
+import {
+  classifyTier,
+  computeHeat,
+  DEFAULT_RECOMMENDER_SETTINGS,
+} from '@/lib/services/berth-recommender.service';
+
+describe('classifyTier', () => {
+  it('"A" when there is no interest history at all', () => {
+    expect(classifyTier({ activeInterestCount: 0, lostCount: 0, maxActiveStage: 0 })).toBe('A');
+  });
+  it('"B" when only lost interests exist (no active)', () => {
+    expect(classifyTier({ activeInterestCount: 0, lostCount: 2, maxActiveStage: 0 })).toBe('B');
+  });
+  it('"C" when an active interest is in an early stage', () => {
+    expect(classifyTier({ activeInterestCount: 1, lostCount: 0, maxActiveStage: 3 })).toBe('C');
+  });
+  it('"C" even when a prior interest was lost, if there is an active one', () => {
+    expect(classifyTier({ activeInterestCount: 1, lostCount: 5, maxActiveStage: 2 })).toBe('C');
+  });
+  it('"D" when an active interest is at deposit or beyond', () => {
+    expect(classifyTier({ activeInterestCount: 1, lostCount: 0, maxActiveStage: 6 })).toBe('D');
+    expect(classifyTier({ activeInterestCount: 1, lostCount: 0, maxActiveStage: 8 })).toBe('D');
+  });
+  it('still "C" at eoi_signed (stage 5) - tier D only kicks in at deposit', () => {
+    expect(classifyTier({ activeInterestCount: 1, lostCount: 0, maxActiveStage: 5 })).toBe('C');
+  });
+});
+
+describe('computeHeat', () => {
+  const w = DEFAULT_RECOMMENDER_SETTINGS;
+  const NOW = new Date('2026-05-05T00:00:00Z');
+
+  it('zero heat when nothing in history', () => {
+    const h = computeHeat(
+      {
+        latestFallthroughAt: null,
+        totalInterestCount: 0,
+        eoiSignedCount: 0,
+        fallthroughMaxStage: 0,
+      },
+      w,
+      NOW,
+    );
+    expect(h.total).toBe(0);
+  });
+
+  it('full recency for a fall-through within the last 30 days', () => {
+    const h = computeHeat(
+      {
+        latestFallthroughAt: new Date('2026-04-25T00:00:00Z'),
+        totalInterestCount: 0,
+        eoiSignedCount: 0,
+        fallthroughMaxStage: 1,
+      },
+      w,
+      NOW,
+    );
+    // recency component should be the full heat_weight_recency (30)
+    expect(h.recency).toBeCloseTo(30, 1);
+  });
+
+  it('zero recency for an ancient fall-through (>1 year)', () => {
+    const h = computeHeat(
+      {
+        latestFallthroughAt: new Date('2024-01-01T00:00:00Z'),
+        totalInterestCount: 0,
+        eoiSignedCount: 0,
+        fallthroughMaxStage: 1,
+      },
+      w,
+      NOW,
+    );
+    expect(h.recency).toBe(0);
+  });
+
+  it('full furthest-stage when the fall-through reached deposit', () => {
+    const h = computeHeat(
+      {
+        latestFallthroughAt: null,
+        totalInterestCount: 0,
+        eoiSignedCount: 0,
+        fallthroughMaxStage: 6, // deposit_10pct
+      },
+      w,
+      NOW,
+    );
+    expect(h.furthestStage).toBeCloseTo(40, 1);
+  });
+
+  it('saturates interest-count at 5+', () => {
+    const h = computeHeat(
+      {
+        latestFallthroughAt: null,
+        totalInterestCount: 10,
+        eoiSignedCount: 0,
+        fallthroughMaxStage: 0,
+      },
+      w,
+      NOW,
+    );
+    expect(h.interestCount).toBeCloseTo(15, 1); // full weight
+  });
+
+  it('saturates EOI-count at 3+', () => {
+    const h = computeHeat(
+      {
+        latestFallthroughAt: null,
+        totalInterestCount: 0,
+        eoiSignedCount: 5,
+        fallthroughMaxStage: 0,
+      },
+      w,
+      NOW,
+    );
+    expect(h.eoiCount).toBeCloseTo(15, 1);
+  });
+
+  it('total ≈ 100 when everything is maxed', () => {
+    const h = computeHeat(
+      {
+        latestFallthroughAt: new Date('2026-04-25T00:00:00Z'),
+        totalInterestCount: 5,
+        eoiSignedCount: 3,
+        fallthroughMaxStage: 6,
+      },
+      w,
+      NOW,
+    );
+    expect(h.total).toBeGreaterThanOrEqual(99);
+    expect(h.total).toBeLessThanOrEqual(100);
+  });
+
+  it('respects tunable per-port weights (skewed toward recency)', () => {
+    const skewed = {
+      heatWeightRecency: 100,
+      heatWeightFurthestStage: 0,
+      heatWeightInterestCount: 0,
+      heatWeightEoiCount: 0,
+    };
+    const recent = computeHeat(
+      {
+        latestFallthroughAt: new Date('2026-04-25T00:00:00Z'),
+        totalInterestCount: 0,
+        eoiSignedCount: 0,
+        fallthroughMaxStage: 0,
+      },
+      skewed,
+      NOW,
+    );
+    expect(recent.total).toBeCloseTo(100, 1);
+
+    const old = computeHeat(
+      {
+        latestFallthroughAt: new Date('2024-01-01T00:00:00Z'),
+        totalInterestCount: 5,
+        eoiSignedCount: 3,
+        fallthroughMaxStage: 6,
+      },
+      skewed,
+      NOW,
+    );
+    expect(old.total).toBe(0);
+  });
+
+  it('zero-weights guard (no division-by-zero blow-up)', () => {
+    const zeros = {
+      heatWeightRecency: 0,
+      heatWeightFurthestStage: 0,
+      heatWeightInterestCount: 0,
+      heatWeightEoiCount: 0,
+    };
+    const h = computeHeat(
+      {
+        latestFallthroughAt: new Date(),
+        totalInterestCount: 5,
+        eoiSignedCount: 3,
+        fallthroughMaxStage: 6,
+      },
+      zeros,
+      NOW,
+    );
+    expect(h.total).toBe(0);
+  });
+});