diff --git a/src/core/search/hybrid.ts b/src/core/search/hybrid.ts
index d6d7b1590..cdfc77978 100644
--- a/src/core/search/hybrid.ts
+++ b/src/core/search/hybrid.ts
@@ -860,6 +860,41 @@ export async function embedQueryBounded(
   }
 }
 
+/**
+ * #3442 — resolve the public `since`/`until` contract (SearchOpts v0.29.1):
+ * ISO-8601 passes through, relative durations ('7d', '2w', '1y') resolve to a
+ * concrete timestamp, and a plain YYYY-MM-DD `until` lands at end-of-day.
+ * The relative form was documented since v0.29.1 but never implemented — the
+ * raw string ('60d') flowed into the engines' `::timestamptz` casts, every
+ * arm failed fail-open, and the date filter was SILENTLY ignored.
+ * Unparseable input now throws loudly instead of degrading.
+ */
+export function resolveDateBoundary(
+  raw: string | undefined,
+  boundary: 'since' | 'until',
+): string | undefined {
+  if (raw === undefined || raw === null) return undefined;
+  const s = String(raw).trim();
+  if (!s) return undefined;
+  const rel = /^(\d+)\s*([dwmy])$/i.exec(s);
+  if (rel) {
+    const n = parseInt(rel[1], 10);
+    const unit = rel[2].toLowerCase();
+    // m = months (30d). Minutes make no sense for an effective_date filter.
+    const days = unit === 'd' ? n : unit === 'w' ? n * 7 : unit === 'm' ? n * 30 : n * 365;
+    return new Date(Date.now() - days * 86400000).toISOString();
+  }
+  if (/^\d{4}-\d{2}-\d{2}$/.test(s)) {
+    // Plain date: `until` lands at end-of-day (documented SearchOpts
+    // semantics); `since` keeps UTC start-of-day.
+    return boundary === 'until' ? `${s}T23:59:59.999Z` : s;
+  }
+  if (Number.isFinite(Date.parse(s))) return s;
+  throw new Error(
+    `Invalid ${boundary} value "${s}" — expected ISO-8601 (YYYY-MM-DD or timestamp) or a relative duration like '7d', '2w', '1y'.`,
+  );
+}
+
 export async function hybridSearch(
   engine: BrainEngine,
   query: string,
@@ -954,8 +989,10 @@ export async function hybridSearch(
     // v0.29.1: since/until take precedence over deprecated afterDate/beforeDate.
     // The engine still consumes the legacy field names; this aliasing keeps
     // PR #618 callers compiling while the new names are the public surface.
-    afterDate: opts?.since ?? opts?.afterDate,
-    beforeDate: opts?.until ?? opts?.beforeDate,
+    // #3442: resolveDateBoundary implements the documented contract (relative
+    // durations + end-of-day for plain-date `until`) at this single seam.
+    afterDate: resolveDateBoundary(opts?.since ?? opts?.afterDate, 'since'),
+    beforeDate: resolveDateBoundary(opts?.until ?? opts?.beforeDate, 'until'),
     // v0.34.1 (#861, D9 — P0 leak seal): thread source-scoping through so the
     // inner engine.searchKeyword / engine.searchVector calls apply the
     // WHERE source_id filter at SQL level. Pre-fix, this explicit pick
@@ -1803,12 +1840,19 @@ export async function hybridSearchCached(
     opts?.adaptiveReturn,
     cfgCached as unknown as Record<string, unknown> | null,
   );
+  // #3442: date-filtered requests skip the cache — since/until are not part
+  // of knobsHash, so a filtered result set could be served to an unfiltered
+  // lookup (and vice versa). Relative forms ('60d') also resolve to a
+  // now-relative timestamp, which a persisted cache row can't express.
+  const dateFiltered =
+    Boolean(opts?.since ?? opts?.afterDate) || Boolean(opts?.until ?? opts?.beforeDate);
   const skipCache =
     !cache.isEnabled() ||
     (opts?.walkDepth ?? 0) > 0 ||
     Boolean(opts?.nearSymbol) ||
     isNonDefaultColumn ||
-    adaptiveReturnOn;
+    adaptiveReturnOn ||
+    dateFiltered;
 
   let cacheStatus: 'hit' | 'miss' | 'disabled' = skipCache ? 'disabled' : 'miss';
   let cacheSimilarity: number | undefined;
diff --git a/test/hybrid-since-relative.serial.test.ts b/test/hybrid-since-relative.serial.test.ts
new file mode 100644
index 000000000..728e35436
--- /dev/null
+++ b/test/hybrid-since-relative.serial.test.ts
@@ -0,0 +1,132 @@
+/**
+ * #3442 — `query --since` relative durations ('7d', '2w', '1y').
+ *
+ * The SearchOpts contract (types.ts, since v0.29.1) and the query op's
+ * --help both document relative durations, but the raw string ('60d')
+ * flowed straight into the engines' `::timestamptz` casts. Every search
+ * arm failed fail-open and the date filter was SILENTLY ignored — the
+ * command still returned results, so the user could not tell the filter
+ * never applied.
+ *
+ * Fix: resolveDateBoundary at the single hybridSearch seam resolves
+ * relative durations to concrete timestamps, lands a plain YYYY-MM-DD
+ * `until` at end-of-day (also documented, also never implemented), and
+ * throws loudly on unparseable input instead of degrading.
+ *
+ * Serial: mutates OPENAI_API_KEY to force the keyword-only path.
+ */
+
+import { afterAll, beforeAll, describe, expect, test } from 'bun:test';
+import { PGLiteEngine } from '../src/core/pglite-engine.ts';
+import { hybridSearch, resolveDateBoundary } from '../src/core/search/hybrid.ts';
+import type { PageInput } from '../src/core/types.ts';
+
+const DAY_MS = 86400000;
+
+describe('resolveDateBoundary (#3442)', () => {
+  test('relative durations resolve to a concrete past timestamp', () => {
+    const cases: Array<[string, number]> = [
+      ['7d', 7],
+      ['60d', 60],
+      ['2w', 14],
+      ['3m', 90],
+      ['1y', 365],
+    ];
+    for (const [raw, days] of cases) {
+      const out = resolveDateBoundary(raw, 'since');
+      expect(out).toBeDefined();
+      const delta = Date.now() - Date.parse(out!);
+      // Within a minute of the expected offset.
+      expect(Math.abs(delta - days * DAY_MS)).toBeLessThan(60_000);
+    }
+  });
+
+  test('ISO dates and timestamps pass through', () => {
+    expect(resolveDateBoundary('2026-06-01', 'since')).toBe('2026-06-01');
+    expect(resolveDateBoundary('2026-06-01T10:00:00Z', 'since')).toBe('2026-06-01T10:00:00Z');
+  });
+
+  test('plain-date `until` lands at end-of-day (documented SearchOpts semantics)', () => {
+    expect(resolveDateBoundary('2026-06-01', 'until')).toBe('2026-06-01T23:59:59.999Z');
+  });
+
+  test('empty/undefined stay undefined', () => {
+    expect(resolveDateBoundary(undefined, 'since')).toBeUndefined();
+    expect(resolveDateBoundary('  ', 'since')).toBeUndefined();
+  });
+
+  test('unparseable input throws loudly instead of silently degrading', () => {
+    expect(() => resolveDateBoundary('sixty days', 'since')).toThrow(/Invalid since value/);
+    expect(() => resolveDateBoundary('60x', 'until')).toThrow(/Invalid until value/);
+  });
+});
+
+describe('hybridSearch since/until end-to-end (#3442)', () => {
+  let engine: PGLiteEngine;
+  const savedKey = process.env.OPENAI_API_KEY;
+
+  beforeAll(async () => {
+    delete process.env.OPENAI_API_KEY; // keyword-only path, no embedding calls
+    engine = new PGLiteEngine();
+    await engine.connect({});
+    await engine.initSchema();
+    await engine.putPage('notes/widget-old', {
+      type: 'note',
+      title: 'Widget Old',
+      compiled_truth:
+        'Widget foundation repair notes from the original crawlspace assessment two years back.',
+    });
+    await engine.putPage('notes/widget-new', {
+      type: 'note',
+      title: 'Widget New',
+      compiled_truth:
+        'Widget foundation repair follow-up: contractor quote for the pier replacement arrived yesterday.',
+    });
+    // putPage does not chunk; give the keyword arm content to match.
+    await engine.upsertChunks('notes/widget-old', [{
+      chunk_index: 0,
+      chunk_text: 'Widget foundation repair notes from the original crawlspace assessment two years back.',
+      chunk_source: 'compiled_truth',
+    }]);
+    await engine.upsertChunks('notes/widget-new', [{
+      chunk_index: 0,
+      chunk_text: 'Widget foundation repair follow-up: contractor quote for the pier replacement arrived yesterday.',
+      chunk_source: 'compiled_truth',
+    }]);
+    await engine.executeRaw(
+      `UPDATE pages SET effective_date = $1 WHERE slug = 'notes/widget-old'`,
+      [new Date(Date.now() - 400 * DAY_MS).toISOString()],
+    );
+    await engine.executeRaw(
+      `UPDATE pages SET effective_date = $1 WHERE slug = 'notes/widget-new'`,
+      [new Date(Date.now() - 1 * DAY_MS).toISOString()],
+    );
+  });
+
+  afterAll(async () => {
+    if (savedKey === undefined) delete process.env.OPENAI_API_KEY;
+    else process.env.OPENAI_API_KEY = savedKey;
+    await engine.disconnect();
+  });
+
+  test('since "60d" filters out old pages (was silently ignored)', async () => {
+    const out = await hybridSearch(engine, 'widget repair', { since: '60d' });
+    const slugs = out.map((r) => r.slug);
+    expect(slugs).toContain('notes/widget-new');
+    expect(slugs).not.toContain('notes/widget-old');
+  });
+
+  test('until "60d" filters out recent pages', async () => {
+    const out = await hybridSearch(engine, 'widget repair', { until: '60d' });
+    const slugs = out.map((r) => r.slug);
+    expect(slugs).toContain('notes/widget-old');
+    expect(slugs).not.toContain('notes/widget-new');
+  });
+
+  test('control: no filter returns both', async () => {
+    const out = await hybridSearch(engine, 'widget repair', {});
+    const slugs = out.map((r) => r.slug);
+    expect(slugs).toContain('notes/widget-new');
+    expect(slugs).toContain('notes/widget-old');
+  });
+});