diff --git a/.sdk-sync/1.4.0-f19c2d4.md b/.sdk-sync/1.4.0-f19c2d4.md
new file mode 100644
index 0000000..c0c51c1
--- /dev/null
+++ b/.sdk-sync/1.4.0-f19c2d4.md
@@ -0,0 +1,101 @@
+# 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 18:45:04Z |
+| Outcome | **done** |
+
+## Changes in the API surface
+
+    ~ GET /v1/options/chain/{underlying}/ ?dte: string  (was integer)
+
+## 1. tests
+
+Coder (23 turns, US$ 0.55):
+
+> The build fails as required, with a compilation error on the not-yet-implemented `ExpirationFilter.dteRange(int, int)` symbol — confirming the tests are correctly specifying new behaviour ahead of implementation.
+> 
+> ## Summary
+> 
+> Added three unit tests to `src/test/java/com/marketdata/sdk/OptionsResourceTest.java` specifying the new behaviour for the `dte` query parameter's `integer` → `string` type change on `GET /v1/options/chain/{underlying}/`, mirroring the existing `?strike=` range convention (`StrikeFilter.range`):
+> 
+> - `chainExpirationFilterDteRangeTranslatesToDashedDteParam` — `ExpirationFilter.dteRange(30, 45)` must translate to `?dte=30-45` on the wire.
+> - `expirationFilterDteRangeRejectsMinGreaterThanMax` — `dteRange(45, 30)` must throw `IllegalArgumentException` ("min must be <= max").
+> - `expirationFilterDteRangeRejectsNegativeMin` — `dteRange(-1, 30)` must throw `IllegalArgumentException` ("dte must be non-negative").
+> 
+> The existing `dte(int)` exact-value tests and validation were left untouched. Ran `gradle test --no-daemon --console=plain`; it fails at `:compileTestJava` because `ExpirationFilter.dteRange(int, int)` doesn't exist yet, confirming the tests correctly drive the required implementation.
+
+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 (11 turns, US$ 0.21):
+
+> All changes are within the allowed paths (`src/main/java`, `src/test/java`, `docs/`), and I did not touch the tests written in phase 1 beyond what already existed.
+> 
+> ## Summary
+> 
+> Implemented the `1.4.0` API change to `GET /v1/options/chain/{underlying}/`'s `dte` query parameter (integer → string), following the same sealed-filter convention `StrikeFilter` already uses for its `?strike=` range syntax:
+> 
+> - `ExpirationFilter`: added a new sealed variant `DteRange(minDays, maxDays)` with factory `ExpirationFilter.dteRange(int, int)`, validating `minDays >= 0` and `minDays <= maxDays` (mirrors `dte(int)`'s and `StrikeFilter.range`'s existing validation messages).
+> - `OptionsResource.applyExpirationFilter`: renders `DteRange` as `?dte=min-max`, keeping the exhaustive if-chain over the now six-variant sealed type complete (no silent no-op for the new case).
+> - `docs/options/chain.md`: documented the new `dteRange(...)` builder call alongside the existing `dte(...)`.
+> 
+> No existing tests were weakened — the phase-1 tests are unchanged and now compile and pass. `gradle test` and `gradle build` (including Spotless and JaCoCo) both succeed.
+
+Gates:
+
+- tests, attempt 1: passed
+- build, attempt 1: passed
+
+## 3. review 1
+
+Reviewer (14 turns, US$ 0.28): approved
+
+> The change correctly implements the API's widening of the options-chain `?dte=` parameter from integer to string by adding a new sealed ExpirationFilter.DteRange variant alongside the existing Dte, serialized as "min-max" on the wire — closely mirroring the established StrikeFilter.Range convention (including matching validation and error messages). The existing single-value `dte(int)` path is untouched and still correct. Tests cover the new URL translation and both validation failure modes (min>max, negative min), matching the depth of coverage given to sibling filter variants in the same test file. Docs (docs/options/chain.md) were updated consistently. No public signatures were broken, no unrelated files were touched, and no existing tests were weakened.
+
+- no findings
+
+Security (7 turns, US$ 0.12): approved
+
+> The change adds ExpirationFilter.dteRange(minDays, maxDays) to support the API's dte int→string widening, formatting the query value as "min-max" from two validated int parameters. Since inputs are constrained to int (not free-form strings), there is no injection risk, and the value still passes through the transport's existing URL-encoding path. Validation (non-negative, min<=max) mirrors the existing Dte/StrikeFilter.range patterns, and tests cover both the happy path and validation errors. No secrets, unsafe defaults, new dependencies, or out-of-scope changes were introduced.
+
+- no findings
+
+## 4. assess
+
+Analyst (3 turns, US$ 0.11) — public surface:
+
+> This change adds a new days-to-expiration range option to the options chain request builder, mirroring the existing strike-range syntax. The sealed ExpirationFilter interface gains a new permitted variant, DteRange, plus a static factory method dteRange(int, int), and its permits list is updated accordingly. OptionsResource is updated internally to translate the new variant to the dte=min-max query wire form, but this is not a public-surface change on its own since OptionsResource's chain-building logic is package-internal branching, not a new/changed public method. No existing public member (type, method, field, or permits entry) was removed or had its signature/behavior changed; all existing ExpirationFilter factory methods and record types are untouched.
+
+- added: `ExpirationFilter.dteRange(int, int)` — New static factory method returning a DteRange filter; throws IllegalArgumentException if minDays is negative or minDays > maxDays. Consumers can now call this method that did not exist before.
+- added: `ExpirationFilter.DteRange` — New public record type (minDays, maxDays) implementing the sealed ExpirationFilter interface; serializes to the chain endpoint's ?dte=min-max wire form.
+- changed: `ExpirationFilter.permits` — The sealed interface's permits list gains ExpirationFilter.DteRange alongside the existing OnDate, Dte, Between, MonthYear, All. Any consumer exhaustive switch over ExpirationFilter without a default branch will no longer compile until a DteRange case is added — a source-compatibility break for that specific pattern, though additive in intent.
+
+Computed by the pipeline: **major**, 1.0.0 → 2.0.0; changelog entry written
+
+## 5. changelog
+
+Coder (3 turns, US$ 0.07):
+
+> Added an `## [Unreleased]` entry noting it responds to API 1.4.0, with an `### Added` line for `ExpirationFilter.dteRange(...)` and a `### Changed` **BREAKING** line explaining the sealed-interface `permits` expansion and how to migrate exhaustive switches.
+
+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: 61
+- Estimated cost: US$ 1.34
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 53c39be..57b3403 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,26 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+Responds to Market Data API release 1.4.0, which widened the options chain
+endpoint's `?dte=` query parameter from an integer to a string so it can carry
+a range in addition to a single value.
+
+### Added
+
+- **`ExpirationFilter.dteRange(int minDays, int maxDays)`** — new
+  days-to-expiration range filter for `client.options().chain(...)`, wire form
+  `?dte=min-max`. Throws `IllegalArgumentException` if `minDays` is negative or
+  greater than `maxDays`.
+
+### Changed
+
+- **BREAKING:** `ExpirationFilter`'s sealed `permits` list gains
+  `ExpirationFilter.DteRange` alongside `OnDate`, `Dte`, `Between`,
+  `MonthYear`, and `All`. Any consumer with an exhaustive `switch` over
+  `ExpirationFilter` and no `default` branch will fail to compile until it
+  adds a `DteRange` case. To migrate, add a case for
+  `ExpirationFilter.DteRange` (or a `default` branch) to any such `switch`.
+
 ## [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..0794778 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.dteRange(int minDays, int maxDays))  // dte 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..ee01d39 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 dteRange(int minDays, int maxDays) {
+    if (minDays < 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..84d93b1 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() {
+    // The chain endpoint's ?dte= param widened from integer to string so it can express a range,
+    // mirroring the existing ?strike= range syntax (StrikeFilter.range -> "min-max").
+    CapturingClient client = okWith(CANNED_CHAIN_BODY);
+    OptionsResource options = resourceWith(client);
+
+    options
+        .chainAsync(
+            OptionsChainRequest.builder("AAPL")
+                .expirationFilter(ExpirationFilter.dteRange(30, 45))
+                .build())
+        .join();
+
+    assertThat(client.captured.get(0).uri().toString())
+        .isEqualTo("http://localhost/v1/options/chain/AAPL/?dte=30-45");
+  }
+
   @Test
   void chainExpirationFilterBetweenTranslatesToFromTo() {
     CapturingClient client = okWith(CANNED_CHAIN_BODY);
@@ -1203,6 +1221,20 @@ void expirationFilterDteRejectsNegative() {
         .hasMessageContaining("dte must be non-negative");
   }
 
+  @Test
+  void expirationFilterDteRangeRejectsMinGreaterThanMax() {
+    assertThatThrownBy(() -> ExpirationFilter.dteRange(45, 30))
+        .isInstanceOf(IllegalArgumentException.class)
+        .hasMessageContaining("min must be <= max");
+  }
+
+  @Test
+  void expirationFilterDteRangeRejectsNegativeMin() {
+    assertThatThrownBy(() -> ExpirationFilter.dteRange(-1, 30))
+        .isInstanceOf(IllegalArgumentException.class)
+        .hasMessageContaining("dte must be non-negative");
+  }
+
   @Test
   void expirationFilterBetweenRejectsReversedDates() {
     assertThatThrownBy(