diff --git a/.sdk-sync/1.4.0-f19c2d4.md b/.sdk-sync/1.4.0-f19c2d4.md
new file mode 100644
index 0000000..2918faf
--- /dev/null
+++ b/.sdk-sync/1.4.0-f19c2d4.md
@@ -0,0 +1,112 @@
+# sdk-auto-sync job log
+
+| | |
+|---|---|
+| API release | 1.4.0 (commit `f19c2d4`) |
+| SDK | sdk-java |
+| Branch | `sdk-sync/1.4.0-f19c2d4` |
+| API surface | `9c18fbb1f58e` → `72b3d15f59ad` |
+| Date | 2026-09-15 19:17:20Z |
+| Outcome | **done** |
+
+## Changes in the API surface
+
+    ~ GET /v1/options/chain/{underlying}/ ?dte: string  (was integer)
+
+## 1. tests
+
+Coder (22 turns, US$ 0.42):
+
+> Only the test file was touched, as required.
+> 
+> ## Summary
+> 
+> The API delta changes `?dte=` on `GET /v1/options/chain/{underlying}/` from `integer` to `string`, mirroring the existing `?strike=` parameter which already accepts a dashed range as a string (`StrikeFilter.range`). I added three tests to `src/test/java/com/marketdata/sdk/OptionsResourceTest.java` that specify the new `ExpirationFilter.dte(int minDays, int maxDays)` range overload, alongside the existing single-value `dte(int)`:
+> 
+> - `chainExpirationFilterDteRangeTranslatesToDashedDteParam` — asserts `ExpirationFilter.dte(30, 60)` serializes the chain request query string as `?dte=30-60`.
+> - `expirationFilterDteRangeRejectsNegativeMin` — asserts `dte(-1, 30)` throws `IllegalArgumentException` ("dte must be non-negative").
+> - `expirationFilterDteRangeRejectsMinGreaterThanMax` — asserts `dte(60, 30)` throws `IllegalArgumentException` ("min must be <= max").
+> 
+> Confirmed `gradle test --no-daemon --console=plain` fails at compilation (the two-arg `dte` overload doesn't exist yet), as expected for this tests-only phase. No production code or docs were touched.
+
+Gates:
+
+- tests (expected to fail), attempt 1: failed — Execution failed for task ':compileTestJava' (registered by plugin class 'org.gradle.api.plugins.JavaBasePlugin').
+
+## 2. implement
+
+Coder (15 turns, US$ 0.28):
+
+> All changes fall within `src/main/java/**`, `src/test/java/**`, and `docs/**`, as required. No commits made.
+> 
+> ## Summary
+> 
+> Implemented `?dte=` widening to `string` on `GET /v1/options/chain/{underlying}/` by adding a days-to-expiration **range** alongside the existing single-value filter:
+> 
+> - `ExpirationFilter.DteRange` — new sealed-interface variant (`minDays`, `maxDays`), added to the `permits` list.
+> - `ExpirationFilter.dte(int minDays, int maxDays)` — new overload of the existing `dte` factory, validating non-negativity and `min <= max` (mirrors `StrikeFilter.range`'s validation style).
+> - `OptionsResource.applyExpirationFilter` — serializes `DteRange` as `?dte=min-max` (e.g. `dte=30-60`), matching the dashed-range convention already used for `?strike=`.
+> - `docs/options/chain.md` — added the new `dte(minDays, maxDays)` builder call to the request-shape listing.
+> 
+> Fixed one Spotless formatting violation in the phase-1 test (line wrap on the range test) — no assertions were weakened. `gradle test` and `gradle build` both pass.
+
+Gates:
+
+- tests, attempt 1: passed
+- build, attempt 1: passed
+
+## 3. review 1
+
+Reviewer (2 turns, US$ 0.32): approved
+
+> The change correctly implements the API's `dte` query-parameter type widening (int → string) by adding a new `ExpirationFilter.DteRange` sealed variant and a `dte(int minDays, int maxDays)` factory, rendering it as the dashed `dte=min-max` wire form. This mirrors the existing `StrikeFilter.range` convention already used in the same file, keeps the sealed interface's `permits` list, javadoc, and validation style consistent with sibling variants (`Dte`, `Between`), updates `OptionsResource.applyExpirationFilter` correctly, and updates `docs/options/chain.md` in the right place. Validation (non-negative bounds, min ≤ max) and error messages match sibling conventions, and new tests cover the happy path and both major validation failure modes. No public-API, convention, or test-weakening issues were found; the only gap is a minor missing test case for the negative-`maxDays` validation branch."
+
+- [minor] src/test/java/com/marketdata/sdk/OptionsResourceTest.java — The new `expirationFilterDteRangeRejectsNegativeMin` test only exercises the `minDays < 0` branch of `ExpirationFilter.dte(int, int)`'s validation. There is no corresponding test for a negative `maxDays` with a non-negative `minDays` (e.g. `dte(5, -1)`), leaving that branch of the `minDays < 0 || maxDays < 0` condition unverified.
+
+Security (4 turns, US$ 0.25): approved
+
+> This change adds ExpirationFilter.dte(int minDays, int maxDays), a new sealed-interface variant producing the wire form ?dte=min-max, matching the API's dte parameter widening from integer to string. Both minDays and maxDays are primitive ints validated non-negative and min<=max before being concatenated into the query value, so there is no injection surface (no free-form string input reaches the query string). The change is narrowly scoped to the stated API update, is fully covered by new unit tests (encoding and validation-rejection paths), and the docs update accurately reflects the new builder method. No secrets, unsafe defaults, altered dependencies, or unrelated modifications were introduced.
+
+- no findings
+
+## 4. assess
+
+Analyst (5 turns, US$ 0.09) — public surface:
+
+> The diff adds one new public surface member (the ExpirationFilter.dte(int minDays, int maxDays) static factory and its backing ExpirationFilter.DteRange record with minDays()/maxDays() accessors) to represent the API's now-string-typed ?dte= range form, and widens the sealed ExpirationFilter interface's permits clause to include DteRange. The existing ExpirationFilter.dte(int days)/Dte record, and all other ExpirationFilter variants, are unchanged in signature. The only surface-breaking effect is on the sealed hierarchy itself: because permits gained a new case, any consumer with an exhaustive switch over ExpirationFilter no longer compiles until a DteRange arm is added — the internal OptionsResource query-translation logic that consumes the new variant is a private helper and not part of the public surface.
+
+- added: `ExpirationFilter.dte(int, int)` — New static factory overload returning ExpirationFilter.DteRange; validates minDays/maxDays non-negative and minDays <= maxDays, translates to wire form ?dte=min-max. Distinct arity from the existing dte(int) overload, so no overload-resolution conflict for existing callers.
+- added: `ExpirationFilter.DteRange` — New public record type implementing ExpirationFilter, with accessors minDays() and maxDays(); added as a new permitted subtype of the sealed interface.
+- changed: `ExpirationFilter.permits` — Sealed interface's permits list now includes ExpirationFilter.DteRange alongside OnDate, Dte, Between, MonthYear, All. Any consumer code that exhaustively switches over ExpirationFilter (relying on compiler-enforced exhaustiveness) will fail to compile until it adds a DteRange case.
+
+Computed by the pipeline: **major**, 1.0.0 → 2.0.0; changelog entry written
+
+## 5. changelog
+
+Coder (3 turns, US$ 0.06):
+
+> Added a `### Changed` entry under `[Unreleased]` documenting the new `ExpirationFilter.dte(int, int)`/`DteRange` range filter (API 1.4.0's `dte` param widening to a string), flagged BREAKING with migration guidance for exhaustive `switch` consumers.
+
+Gates:
+
+- build, attempt 1: passed
+
+## Totals
+
+- Version: major · 1.0.0 → 2.0.0
+- Coder runs: 3
+- Review runs: 2
+- Gates run: 4 (1 failed)
+- Files changed by the agent: 5
+- Turns: 51
+- Tokens: 2,398,386
+- Estimated cost: US$ 1.43
+
+### Agent runs
+
+- coder · claude-haiku-4-5-20251001, claude-sonnet-5 · 950,333 tokens (939,677 in, 10,656 out) · 22 turns · US$ 0.42
+- coder · claude-sonnet-5 · 974,788 tokens (970,820 in, 3,968 out) · 15 turns · US$ 0.28
+- reviewer · claude-haiku-4-5-20251001, claude-sonnet-5 · 64,892 tokens (56,064 in, 8,828 out) · 2 turns · US$ 0.32
+- security · claude-haiku-4-5-20251001, claude-sonnet-5 · 113,651 tokens (112,635 in, 1,016 out) · 4 turns · US$ 0.25
+- analyst · claude-haiku-4-5-20251001, claude-sonnet-5 · 76,526 tokens (74,375 in, 2,151 out) · 5 turns · US$ 0.09
+- coder · claude-sonnet-5 · 218,196 tokens (217,473 in, 723 out) · 3 turns · US$ 0.06
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 53c39be..82d9f04 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,20 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Changed
+
+- **BREAKING:** `ExpirationFilter.dte` now also accepts a days-to-expiration
+  range (`ExpirationFilter.dte(minDays, maxDays)`), translating to the wire
+  form `?dte=min-max`, in response to the Market Data API 1.4.0 change
+  widening the options chain `dte` query parameter from an integer to a
+  string. This adds `ExpirationFilter.DteRange` as a new permitted subtype of
+  the sealed `ExpirationFilter` interface, so any code that exhaustively
+  `switch`es over `ExpirationFilter` will fail to compile until it adds a
+  `DteRange` case — add a branch (e.g. `case ExpirationFilter.DteRange r -> …`)
+  alongside the existing `OnDate` / `Dte` / `Between` / `MonthYear` / `All`
+  cases. The existing single-value `ExpirationFilter.dte(int)` overload and
+  its `?dte=N` wire form are unchanged.
+
 ## [1.0.0] - 2026-06-29
 
 First stable release of the Market Data Java &amp; Kotlin SDK — a single JVM
diff --git a/docs/options/chain.md b/docs/options/chain.md
index d71c38b..54eb442 100644
--- a/docs/options/chain.md
+++ b/docs/options/chain.md
@@ -21,6 +21,7 @@ OptionsChainRequest.builder(String symbol)
     // Expiration selection (sealed ExpirationFilter — pick one):
     .expirationFilter(ExpirationFilter.onDate(LocalDate date))
     .expirationFilter(ExpirationFilter.dte(int days))          // days-to-expiration
+    .expirationFilter(ExpirationFilter.dte(int minDays, int maxDays))  // days-to-expiration range
     .expirationFilter(ExpirationFilter.between(LocalDate from, LocalDate to))
     .expirationFilter(ExpirationFilter.all())                  // every expiration
     // (if omitted, the API narrows to the front month)
diff --git a/src/main/java/com/marketdata/sdk/OptionsResource.java b/src/main/java/com/marketdata/sdk/OptionsResource.java
index 81fc7ee..00ec485 100644
--- a/src/main/java/com/marketdata/sdk/OptionsResource.java
+++ b/src/main/java/com/marketdata/sdk/OptionsResource.java
@@ -312,6 +312,8 @@ private static void applyExpirationFilter(RequestSpec.Builder b, ExpirationFilte
       b.query("expiration", DateTimeFormatter.ISO_LOCAL_DATE.format(v.date()));
     } else if (f instanceof ExpirationFilter.Dte v) {
       b.query("dte", v.days());
+    } else if (f instanceof ExpirationFilter.DteRange v) {
+      b.query("dte", v.minDays() + "-" + v.maxDays());
     } else if (f instanceof ExpirationFilter.Between v) {
       b.query("from", DateTimeFormatter.ISO_LOCAL_DATE.format(v.from()));
       b.query("to", DateTimeFormatter.ISO_LOCAL_DATE.format(v.to()));
diff --git a/src/main/java/com/marketdata/sdk/options/ExpirationFilter.java b/src/main/java/com/marketdata/sdk/options/ExpirationFilter.java
index 3b05379..b8653b0 100644
--- a/src/main/java/com/marketdata/sdk/options/ExpirationFilter.java
+++ b/src/main/java/com/marketdata/sdk/options/ExpirationFilter.java
@@ -18,6 +18,7 @@
 public sealed interface ExpirationFilter
     permits ExpirationFilter.OnDate,
         ExpirationFilter.Dte,
+        ExpirationFilter.DteRange,
         ExpirationFilter.Between,
         ExpirationFilter.MonthYear,
         ExpirationFilter.All {
@@ -47,6 +48,20 @@ static Dte dte(int days) {
     return new Dte(days);
   }
 
+  /**
+   * Days-to-expiration range — wire form {@code ?dte=min-max}. {@code minDays} must not exceed
+   * {@code maxDays}.
+   */
+  static DteRange dte(int minDays, int maxDays) {
+    if (minDays < 0 || maxDays < 0) {
+      throw new IllegalArgumentException("dte must be non-negative");
+    }
+    if (minDays > maxDays) {
+      throw new IllegalArgumentException("min must be <= max");
+    }
+    return new DteRange(minDays, maxDays);
+  }
+
   /**
    * Inclusive date range — wire form {@code ?from=YYYY-MM-DD&to=YYYY-MM-DD}. {@code from} must not
    * be strictly after {@code to}.
@@ -79,6 +94,8 @@ record OnDate(LocalDate date) implements ExpirationFilter {
 
   record Dte(int days) implements ExpirationFilter {}
 
+  record DteRange(int minDays, int maxDays) implements ExpirationFilter {}
+
   record Between(LocalDate from, LocalDate to) implements ExpirationFilter {}
 
   record MonthYear(int year, int month) implements ExpirationFilter {}
diff --git a/src/test/java/com/marketdata/sdk/OptionsResourceTest.java b/src/test/java/com/marketdata/sdk/OptionsResourceTest.java
index 292ee83..4900f6b 100644
--- a/src/test/java/com/marketdata/sdk/OptionsResourceTest.java
+++ b/src/test/java/com/marketdata/sdk/OptionsResourceTest.java
@@ -975,6 +975,24 @@ void chainExpirationFilterDteTranslatesToDteParam() {
         .isEqualTo("http://localhost/v1/options/chain/AAPL/?dte=30");
   }
 
+  @Test
+  void chainExpirationFilterDteRangeTranslatesToDashedDteParam() {
+    // §11.4-delta: ?dte= now accepts a string, widening the single day count to a "min-max" range
+    // (mirrors StrikeFilter.range's dashed wire form for ?strike=).
+    CapturingClient client = okWith(CANNED_CHAIN_BODY);
+    OptionsResource options = resourceWith(client);
+
+    options
+        .chainAsync(
+            OptionsChainRequest.builder("AAPL")
+                .expirationFilter(ExpirationFilter.dte(30, 60))
+                .build())
+        .join();
+
+    assertThat(client.captured.get(0).uri().toString())
+        .isEqualTo("http://localhost/v1/options/chain/AAPL/?dte=30-60");
+  }
+
   @Test
   void chainExpirationFilterBetweenTranslatesToFromTo() {
     CapturingClient client = okWith(CANNED_CHAIN_BODY);
@@ -1203,6 +1221,20 @@ void expirationFilterDteRejectsNegative() {
         .hasMessageContaining("dte must be non-negative");
   }
 
+  @Test
+  void expirationFilterDteRangeRejectsNegativeMin() {
+    assertThatThrownBy(() -> ExpirationFilter.dte(-1, 30))
+        .isInstanceOf(IllegalArgumentException.class)
+        .hasMessageContaining("dte must be non-negative");
+  }
+
+  @Test
+  void expirationFilterDteRangeRejectsMinGreaterThanMax() {
+    assertThatThrownBy(() -> ExpirationFilter.dte(60, 30))
+        .isInstanceOf(IllegalArgumentException.class)
+        .hasMessageContaining("min must be <= max");
+  }
+
   @Test
   void expirationFilterBetweenRejectsReversedDates() {
     assertThatThrownBy(