diff --git a/.github/scripts/release_verify.py b/.github/scripts/release_verify.py
index 7f69f2408..dcfbd5ad5 100644
--- a/.github/scripts/release_verify.py
+++ b/.github/scripts/release_verify.py
@@ -108,6 +108,42 @@ def verify_dist(args: argparse.Namespace) -> None:
         print(f"  {name}")
 
 
+def changelog_notes(args: argparse.Namespace) -> None:
+    changelog_path = pathlib.Path(args.changelog)
+    lines = changelog_path.read_text(encoding="utf-8").splitlines()
+    heading = re.compile(r"^## \[(?P<version>[^\]]+)\](?:\s+-\s+.*)?\s*$")
+
+    start = None
+    for index, line in enumerate(lines):
+        match = heading.match(line)
+        if match and match.group("version") == args.version:
+            start = index + 1
+            break
+
+    if start is None:
+        raise RuntimeError(
+            f"Could not find changelog section for version {args.version!r}"
+        )
+
+    end = len(lines)
+    for index in range(start, len(lines)):
+        if lines[index].startswith("## "):
+            end = index
+            break
+
+    section_lines = lines[start:end]
+    while section_lines and not section_lines[0].strip():
+        section_lines.pop(0)
+    while section_lines and not section_lines[-1].strip():
+        section_lines.pop()
+
+    if not section_lines:
+        raise RuntimeError(f"Changelog section for {args.version!r} is empty")
+
+    notes = "## Changelog\n\n" + "\n".join(section_lines) + "\n"
+    pathlib.Path(args.output).write_text(notes, encoding="utf-8")
+
+
 def main(argv: Sequence[str] | None = None) -> None:
     parser = argparse.ArgumentParser()
     subparsers = parser.add_subparsers(required=True)
@@ -122,6 +158,12 @@ def main(argv: Sequence[str] | None = None) -> None:
     verify_parser.add_argument("--dist-dir", default="dist")
     verify_parser.set_defaults(func=verify_dist)
 
+    changelog_parser = subparsers.add_parser("changelog-notes")
+    changelog_parser.add_argument("--version", required=True)
+    changelog_parser.add_argument("--changelog", default="CHANGELOG.md")
+    changelog_parser.add_argument("--output", required=True)
+    changelog_parser.set_defaults(func=changelog_notes)
+
     args = parser.parse_args(argv)
     args.func(args)
 
diff --git a/.github/workflows/release-publish.yml b/.github/workflows/release-publish.yml
index 5c8d54196..5f4cdfc74 100644
--- a/.github/workflows/release-publish.yml
+++ b/.github/workflows/release-publish.yml
@@ -111,6 +111,12 @@ jobs:
           python .github/scripts/release_verify.py validate-version \
             --sha "$(git rev-parse HEAD)" \
             --github-output "$GITHUB_OUTPUT"
+      - name: Validate changelog release notes
+        run: |
+          set -euo pipefail
+          python .github/scripts/release_verify.py changelog-notes \
+            --version "${{ steps.validate_versions.outputs.version }}" \
+            --output /tmp/release-notes.md
       - name: Download and flatten artifacts
         env:
           GH_TOKEN: ${{ github.token }}
@@ -249,6 +255,17 @@ jobs:
     permissions:
       contents: write
     steps:
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
+        with:
+          ref: ${{ needs.verify_artifacts.outputs.release_sha }}
+      - name: Build changelog release notes
+        env:
+          VERSION: ${{ needs.verify_artifacts.outputs.version }}
+        run: |
+          set -euo pipefail
+          python3 .github/scripts/release_verify.py changelog-notes \
+            --version "$VERSION" \
+            --output release-notes.md
       - name: Create draft release with generated notes
         env:
           GH_TOKEN: ${{ github.token }}
@@ -261,4 +278,5 @@ jobs:
             --target "$RELEASE_SHA" \
             --title "$VERSION" \
             --draft \
+            --notes-file release-notes.md \
             --generate-notes
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 346a0bcb3..9c975cfec 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -19,8 +19,41 @@ to docs, or any other relevant information.
 
 ## [Unreleased]
 
+## [1.29.0] - 2026-06-17
+
+### Added
+
+- Added experimental `temporalio.workflow.signal_with_start_workflow`, backed by
+  generated system Nexus bindings for
+  `WorkflowService.SignalWithStartWorkflowExecution`.
+- Added OpenAI Agents plugin support for `CustomTool` dispatch, including lazy
+  tool discovery through `defer_loading`.
+
+### Changed
+
+- Client connections now use gzip transport-level gRPC compression by default.
+  Pass `grpc_compression=GrpcCompression.NONE` to `Client.connect` or
+  `CloudOperationsClient.connect` to disable it.
+
+### Breaking Changes
+
+- `StartWorkflowUpdateWithStartInput` now owns the authoritative
+  `rpc_metadata` and `rpc_timeout` fields for
+  `OutboundInterceptor.start_update_with_start_workflow`. These fields were
+  removed from the nested update-with-start input objects, so custom
+  interceptors that accessed them there should read or update the top-level
+  fields instead.
+
 ### Fixed
 
+- Fixed `breakpoint()` and `pdb.set_trace()` inside workflow code when a worker
+  runs with `debug_mode=True` or `TEMPORAL_DEBUG=1`; sandboxed workflows without
+  debug mode now get a clearer error pointing to `debug_mode=True`.
+- Fixed `start_update_with_start_workflow` interceptor handling so RPC metadata
+  and timeouts are forwarded to the underlying `execute_multi_operation` call.
+- Fixed OpenAI Agents plugin streamed event serialization when pydantic had not
+  yet built deferred schemas, and fixed terminal sandbox errors retrying
+  forever.
 - Removed the lazy-connect lock from the per-RPC hot path. It was previously
   acquired on every RPC, putting an event-loop-bound primitive on the hot path;
   it is now skipped once the client is connected. This reduces the client's
diff --git a/pyproject.toml b/pyproject.toml
index 943e56018..299c03df9 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "temporalio"
-version = "1.28.0"
+version = "1.29.0"
 description = "Temporal.io Python SDK"
 authors = [{ name = "Temporal Technologies Inc", email = "sdk@temporal.io" }]
 requires-python = ">=3.10"
diff --git a/temporalio/service.py b/temporalio/service.py
index 3d8702ed1..2d3829c08 100644
--- a/temporalio/service.py
+++ b/temporalio/service.py
@@ -24,7 +24,7 @@
 import temporalio.runtime
 from temporalio.bridge.client import RPCError as BridgeRPCError
 
-__version__ = "1.28.0"
+__version__ = "1.29.0"
 
 ServiceRequest = TypeVar("ServiceRequest", bound=google.protobuf.message.Message)
 ServiceResponse = TypeVar("ServiceResponse", bound=google.protobuf.message.Message)
diff --git a/uv.lock b/uv.lock
index 15a79011a..3e48e3df7 100644
--- a/uv.lock
+++ b/uv.lock
@@ -5412,7 +5412,7 @@ wheels = [
 
 [[package]]
 name = "temporalio"
-version = "1.28.0"
+version = "1.29.0"
 source = { virtual = "." }
 dependencies = [
     { name = "nexus-rpc" },