diff --git a/recipes/dedupe_triggers.proto b/recipes/dedupe_triggers.proto
new file mode 100644
index 0000000..12a6a95
--- /dev/null
+++ b/recipes/dedupe_triggers.proto
@@ -0,0 +1,25 @@
+// Copyright 2026 The Pigweed Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may not
+// use this file except in compliance with the License. You may obtain a copy of
+// the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+// License for the specific language governing permissions and limitations under
+// the License.
+
+syntax = "proto3";
+
+package recipes.pigweed.dedupe_triggers;
+
+message InputProperties {
+  // Builder in the same bucket to trigger.
+  string builder = 1;
+
+  // Whether deduplication is enabled. If false, always launches subbuild.
+  bool enabled = 2;
+}
diff --git a/recipes/dedupe_triggers.py b/recipes/dedupe_triggers.py
new file mode 100644
index 0000000..4fa6db3
--- /dev/null
+++ b/recipes/dedupe_triggers.py
@@ -0,0 +1,623 @@
+# Copyright 2026 The Pigweed Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may not
+# use this file except in compliance with the License. You may obtain a copy of
+# the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations under
+# the License.
+"""Deduplicates builder triggers by commit.
+
+This recipe looks for recent builds over the past week with an input commit that
+matches its triggering commit. Only the commit has to match, not the branch or
+repository.
+
+If enabled:
+* If there are completed matching builds, it creates an empty step with a link
+  to the most recent completed build and duplicates its output properties and
+  build summary.
+* If there are matching builds still running that have higher Buildbucket IDs
+  than the current build (meaning they were created earlier), it waits until
+  the build completes and then creates an empty step with a link to the
+  completed build and duplicates its output properties and build summary.
+* If there are no other matching builds (or any running matching builds have
+  lower Buildbucket IDs and were created later), it triggers the target builder
+  in the same bucket, waits until it completes, and duplicates its output
+  properties and build summary.
+
+If not enabled:
+* It searches for matching builds and lists what it would have done if enabled,
+  but always launches the subbuild and uses its output.
+"""
+
+from __future__ import annotations
+
+import datetime
+from collections.abc import Iterator
+
+from google.protobuf import json_format
+
+from recipe_engine import post_process, recipe_api, recipe_test_api
+
+from PB.go.chromium.org.luci.buildbucket.proto import build as build_pb
+from PB.go.chromium.org.luci.buildbucket.proto import (
+    builds_service as builds_service_pb,
+)
+from PB.go.chromium.org.luci.buildbucket.proto import common as common_pb
+from PB.recipe_engine import result as result_pb
+from PB.recipes.pigweed.dedupe_triggers import InputProperties
+
+from RECIPE_MODULES.pigweed.raw_result import api as raw_result_api
+
+DEPS = [
+    'pigweed/raw_result',
+    'recipe_engine/buildbucket',
+    'recipe_engine/properties',
+    'recipe_engine/step',
+    'recipe_engine/time',
+]
+
+PROPERTIES = InputProperties
+
+
+def _duplicate_build_output(
+    api: recipe_api.RecipeScriptApi,
+    build: build_pb.Build,
+    step_name: str,
+) -> result_pb.RawResult:
+    pres = api.step.empty(step_name).presentation
+    pres.links[str(build.id)] = api.buildbucket.build_url(build_id=build.id)
+    output_props = json_format.MessageToDict(build.output.properties)
+    for key, value in output_props.items():
+        pres.properties[key] = value
+
+    return result_pb.RawResult(
+        summary_markdown=build.summary_markdown,
+        status=build.status or common_pb.SUCCESS,
+    )
+
+
+def _trigger_and_collect(
+    api: recipe_api.RecipeScriptApi,
+    builder: str,
+) -> result_pb.RawResult:
+    req = api.buildbucket.schedule_request(
+        builder=builder,
+    )
+    scheduled = api.buildbucket.schedule([req])
+    subbuild = scheduled[0]
+    completed = api.buildbucket.collect_build(
+        subbuild.id,
+        fields=api.buildbucket.DEFAULT_FIELDS | {'summary_markdown'},
+    )
+    return _duplicate_build_output(api, completed, f'subbuild {completed.id}')
+
+
+@raw_result_api.wrap_run_steps
+def RunSteps(
+    api: recipe_api.RecipeScriptApi,
+    props: InputProperties,
+) -> result_pb.RawResult | None:
+    if not props.builder:
+        raise api.step.StepFailure('Target builder property not specified')
+
+    commit = api.buildbucket.gitiles_commit
+    commit_id = commit.id if commit else ''
+
+    predicate = builds_service_pb.BuildPredicate()
+    predicate.builder.project = api.buildbucket.build.builder.project
+    predicate.builder.bucket = api.buildbucket.build.builder.bucket
+    predicate.builder.builder = props.builder
+
+    now = api.time.utcnow()
+    start_time = now - datetime.timedelta(days=7)
+    predicate.create_time.start_time.FromDatetime(start_time)
+
+    builds = api.buildbucket.search(
+        predicate,
+        fields=api.buildbucket.DEFAULT_FIELDS | {'summary_markdown'},
+    )
+
+    matching_builds = [
+        b
+        for b in builds
+        if b.id != api.buildbucket.build.id
+        and commit_id
+        and b.input.gitiles_commit.id == commit_id
+    ]
+
+    completed_builds = [
+        b for b in matching_builds if b.status & common_pb.ENDED_MASK
+    ]
+    completed_builds.sort(
+        key=lambda b: (b.create_time.seconds, b.create_time.nanos, -b.id),
+        reverse=True,
+    )
+    running_earlier_builds = [
+        b
+        for b in matching_builds
+        if not (b.status & common_pb.ENDED_MASK)
+        and b.id > api.buildbucket.build.id
+    ]
+    running_earlier_builds.sort(
+        key=lambda b: (b.create_time.seconds, b.create_time.nanos, -b.id),
+        reverse=True,
+    )
+
+    if props.enabled:
+        if completed_builds:
+            target = completed_builds[0]
+            return _duplicate_build_output(
+                api, target, f'reused completed build {target.id}'
+            )
+
+        if running_earlier_builds:
+            target = running_earlier_builds[0]
+            completed = api.buildbucket.collect_build(
+                target.id,
+                fields=api.buildbucket.DEFAULT_FIELDS | {'summary_markdown'},
+            )
+            return _duplicate_build_output(
+                api, completed, f'reused completed build {completed.id}'
+            )
+
+        return _trigger_and_collect(api, props.builder)
+
+    if completed_builds:
+        target = completed_builds[0]
+        pres = api.step.empty(
+            f'would have reused completed build {target.id}'
+        ).presentation
+        pres.links[str(target.id)] = api.buildbucket.build_url(
+            build_id=target.id
+        )
+
+    elif running_earlier_builds:
+        target = running_earlier_builds[0]
+        pres = api.step.empty(
+            f'would have waited for running build {target.id}'
+        ).presentation
+        pres.links[str(target.id)] = api.buildbucket.build_url(
+            build_id=target.id
+        )
+
+    else:
+        api.step.empty(
+            'no matching builds to reuse, would have triggered '
+            f'{props.builder} anyway'
+        )
+
+    return _trigger_and_collect(api, props.builder)
+
+
+def GenTests(
+    api: recipe_test_api.RecipeTestApi,
+) -> Iterator[recipe_test_api.TestData]:
+    target_builder = 'target-builder'
+    test_commit = '1111111111111111111111111111111111111111'
+    current_build_id = 5000000000000000000
+
+    def current_build(**kwargs) -> recipe_test_api.TestData:
+        return api.buildbucket.ci_build(
+            project='pigweed',
+            bucket='ci',
+            builder='dedupe-builder',
+            git_repo='https://pigweed.googlesource.com/pigweed/pigweed',
+            revision=test_commit,
+            build_id=current_build_id,
+            **kwargs,
+        )
+
+    def search_result(*builds: build_pb.Build) -> recipe_test_api.TestData:
+        return api.buildbucket.simulated_search_results(list(builds))
+
+    # Test 1: Completed build found, enabled=True -> Reuses completed build.
+    completed_build = api.buildbucket.ci_build_message(
+        project='pigweed',
+        bucket='ci',
+        builder=target_builder,
+        git_repo='https://pigweed.googlesource.com/pigweed/pigweed',
+        revision=test_commit,
+        build_id=6000000000000000000,
+        status='SUCCESS',
+        summary_markdown='Target build succeeded',
+    )
+    completed_build.output.properties['output_prop'] = 'val1'
+
+    yield (
+        api.test('completed_build_enabled')
+        + current_build()
+        + api.properties(
+            InputProperties(
+                builder=target_builder,
+                enabled=True,
+            )
+        )
+        + search_result(completed_build)
+        + api.post_check(
+            post_process.MustRun,
+            'reused completed build 6000000000000000000',
+        )
+        + api.post_check(
+            post_process.SummaryMarkdown,
+            'Target build succeeded',
+        )
+        + api.post_check(
+            post_process.PropertyEquals,
+            'output_prop',
+            'val1',
+        )
+        + api.post_check(
+            post_process.DoesNotRun,
+            'buildbucket.schedule',
+        )
+        + api.post_process(post_process.DropExpectation)
+    )
+
+    # Test 2: Completed build found with different repo/branch, enabled=True
+    # Only commit has to match.
+    diff_repo_build = api.buildbucket.ci_build_message(
+        project='other_proj',
+        bucket='ci',
+        builder=target_builder,
+        git_repo='https://pigweed.googlesource.com/other/repo',
+        git_ref='refs/heads/other-branch',
+        revision=test_commit,
+        build_id=6000000000000000001,
+        status='SUCCESS',
+        summary_markdown='Different repo build succeeded',
+    )
+    diff_repo_build.output.properties['diff_prop'] = 'diff_val'
+
+    yield (
+        api.test('completed_build_different_repo_branch')
+        + current_build()
+        + api.properties(
+            InputProperties(
+                builder=target_builder,
+                enabled=True,
+            )
+        )
+        + search_result(diff_repo_build)
+        + api.post_check(
+            post_process.MustRun,
+            'reused completed build 6000000000000000001',
+        )
+        + api.post_check(
+            post_process.PropertyEquals,
+            'diff_prop',
+            'diff_val',
+        )
+        + api.post_process(post_process.DropExpectation)
+    )
+
+    # Test 3: Running build created earlier (higher ID), enabled=True -> Waits
+    # and reuses.
+    running_earlier_build = api.buildbucket.ci_build_message(
+        project='pigweed',
+        bucket='ci',
+        builder=target_builder,
+        git_repo='https://pigweed.googlesource.com/pigweed/pigweed',
+        revision=test_commit,
+        build_id=current_build_id + 1000,
+        status='STARTED',
+    )
+    collected_running_build = api.buildbucket.ci_build_message(
+        project='pigweed',
+        bucket='ci',
+        builder=target_builder,
+        git_repo='https://pigweed.googlesource.com/pigweed/pigweed',
+        revision=test_commit,
+        build_id=current_build_id + 1000,
+        status='SUCCESS',
+        summary_markdown='Waited build finished successfully',
+    )
+    collected_running_build.output.properties['running_prop'] = 'running_val'
+
+    yield (
+        api.test('running_build_created_earlier_enabled')
+        + current_build()
+        + api.properties(
+            InputProperties(
+                builder=target_builder,
+                enabled=True,
+            )
+        )
+        + search_result(running_earlier_build)
+        + api.buildbucket.simulated_collect_output([collected_running_build])
+        + api.post_check(
+            post_process.MustRun,
+            f'reused completed build {current_build_id + 1000}',
+        )
+        + api.post_check(
+            post_process.SummaryMarkdown,
+            'Waited build finished successfully',
+        )
+        + api.post_check(
+            post_process.PropertyEquals,
+            'running_prop',
+            'running_val',
+        )
+        + api.post_check(
+            post_process.DoesNotRun,
+            'buildbucket.schedule',
+        )
+        + api.post_process(post_process.DropExpectation)
+    )
+
+    subbuild_id = 8945511751514863184
+    subbuild_collected = api.buildbucket.ci_build_message(
+        project='pigweed',
+        bucket='ci',
+        builder=target_builder,
+        git_repo='https://pigweed.googlesource.com/pigweed/pigweed',
+        revision=test_commit,
+        build_id=subbuild_id,
+        status='SUCCESS',
+        summary_markdown='New subbuild completed',
+    )
+    subbuild_collected.output.properties['sub_prop'] = 'sub_val'
+
+    def simulate_subbuild(build: build_pb.Build) -> recipe_test_api.TestData:
+        return api.buildbucket.simulated_schedule_output(
+            batch_response=builds_service_pb.BatchResponse(
+                responses=[
+                    dict(
+                        schedule_build=dict(
+                            id=build.id,
+                            builder=build.builder,
+                        )
+                    )
+                ]
+            )
+        ) + api.buildbucket.simulated_collect_output([build])
+
+    # Test 4: Running build created later (lower ID), enabled=True -> Triggers
+    # new subbuild.
+    running_later_build = api.buildbucket.ci_build_message(
+        project='pigweed',
+        bucket='ci',
+        builder=target_builder,
+        git_repo='https://pigweed.googlesource.com/pigweed/pigweed',
+        revision=test_commit,
+        build_id=current_build_id - 1000,
+        status='STARTED',
+    )
+
+    yield (
+        api.test('running_build_created_later_enabled')
+        + current_build()
+        + api.properties(
+            InputProperties(
+                builder=target_builder,
+                enabled=True,
+            )
+        )
+        + search_result(running_later_build)
+        + simulate_subbuild(subbuild_collected)
+        + api.post_check(
+            post_process.MustRun,
+            'buildbucket.schedule',
+        )
+        + api.post_check(
+            post_process.MustRun,
+            f'subbuild {subbuild_id}',
+        )
+        + api.post_check(
+            post_process.PropertyEquals,
+            'sub_prop',
+            'sub_val',
+        )
+        + api.post_process(post_process.DropExpectation)
+    )
+
+    # Test 5: No matching builds found, enabled=True -> Triggers subbuild.
+    other_commit_build = api.buildbucket.ci_build_message(
+        project='pigweed',
+        bucket='ci',
+        builder=target_builder,
+        git_repo='https://pigweed.googlesource.com/pigweed/pigweed',
+        revision='2222222222222222222222222222222222222222',
+        build_id=6000000000000000005,
+        status='SUCCESS',
+    )
+
+    yield (
+        api.test('no_other_builds_enabled')
+        + current_build()
+        + api.properties(
+            InputProperties(
+                builder=target_builder,
+                enabled=True,
+            )
+        )
+        + search_result(other_commit_build)
+        + simulate_subbuild(subbuild_collected)
+        + api.post_check(
+            post_process.MustRun,
+            'buildbucket.schedule',
+        )
+        + api.post_check(
+            post_process.MustRun,
+            f'subbuild {subbuild_id}',
+        )
+        + api.post_process(post_process.DropExpectation)
+    )
+
+    # Test 6: Disabled, completed build exists -> Lists would have reused,
+    # triggers subbuild.
+    yield (
+        api.test('disabled_with_completed_build')
+        + current_build()
+        + api.properties(
+            InputProperties(
+                builder=target_builder,
+                enabled=False,
+            )
+        )
+        + search_result(completed_build)
+        + simulate_subbuild(subbuild_collected)
+        + api.post_check(
+            post_process.MustRun,
+            'would have reused completed build 6000000000000000000',
+        )
+        + api.post_check(
+            post_process.MustRun,
+            'buildbucket.schedule',
+        )
+        + api.post_check(
+            post_process.MustRun,
+            f'subbuild {subbuild_id}',
+        )
+        + api.post_process(post_process.DropExpectation)
+    )
+
+    # Test 7: Disabled, running earlier build exists -> Lists would have
+    # waited, triggers subbuild.
+    yield (
+        api.test('disabled_with_running_earlier_build')
+        + current_build()
+        + api.properties(
+            InputProperties(
+                builder=target_builder,
+                enabled=False,
+            )
+        )
+        + search_result(running_earlier_build)
+        + simulate_subbuild(subbuild_collected)
+        + api.post_check(
+            post_process.MustRun,
+            f'would have waited for running build {current_build_id + 1000}',
+        )
+        + api.post_check(
+            post_process.MustRun,
+            'buildbucket.schedule',
+        )
+        + api.post_process(post_process.DropExpectation)
+    )
+
+    # Test 8: Disabled, no matching builds -> Lists would have triggered,
+    # triggers subbuild.
+    yield (
+        api.test('disabled_with_no_builds')
+        + current_build()
+        + api.properties(
+            InputProperties(
+                builder=target_builder,
+                enabled=False,
+            )
+        )
+        + search_result()
+        + simulate_subbuild(subbuild_collected)
+        + api.post_check(
+            post_process.MustRun,
+            f'no matching builds to reuse, would have triggered {target_builder} anyway',
+        )
+        + api.post_check(
+            post_process.MustRun,
+            'buildbucket.schedule',
+        )
+        + api.post_process(post_process.DropExpectation)
+    )
+
+    # Test 9: No builder specified -> StepFailure
+    yield (
+        api.test('no_builder_specified', status='FAILURE')
+        + current_build()
+        + api.properties(
+            InputProperties(
+                builder='',
+                enabled=True,
+            )
+        )
+        + api.post_process(post_process.StatusFailure)
+        + api.post_process(post_process.DropExpectation)
+    )
+
+    # Test 10: Reused build failure status and summary propagation.
+    failed_build = api.buildbucket.ci_build_message(
+        project='pigweed',
+        bucket='ci',
+        builder=target_builder,
+        git_repo='https://pigweed.googlesource.com/pigweed/pigweed',
+        revision=test_commit,
+        build_id=6000000000000000010,
+        status='FAILURE',
+        summary_markdown='Compilation error on target',
+    )
+
+    yield (
+        api.test('reused_build_failure', status='FAILURE')
+        + current_build()
+        + api.properties(
+            InputProperties(
+                builder=target_builder,
+                enabled=True,
+            )
+        )
+        + search_result(failed_build)
+        + api.post_process(post_process.StatusFailure)
+        + api.post_check(
+            post_process.SummaryMarkdown,
+            'Compilation error on target',
+        )
+        + api.post_process(post_process.DropExpectation)
+    )
+
+    # Test 11: Multiple completed matching builds -> Most recent one is used.
+    older_completed_build = api.buildbucket.ci_build_message(
+        project='pigweed',
+        bucket='ci',
+        builder=target_builder,
+        git_repo='https://pigweed.googlesource.com/pigweed/pigweed',
+        revision=test_commit,
+        build_id=7000000000000000000,
+        status='SUCCESS',
+        summary_markdown='Older build summary',
+    )
+    older_completed_build.output.properties['which_build'] = 'older'
+    older_completed_build.create_time.seconds = 1500000000
+
+    newer_completed_build = api.buildbucket.ci_build_message(
+        project='pigweed',
+        bucket='ci',
+        builder=target_builder,
+        git_repo='https://pigweed.googlesource.com/pigweed/pigweed',
+        revision=test_commit,
+        build_id=6000000000000000000,
+        status='SUCCESS',
+        summary_markdown='Newer build summary',
+    )
+    newer_completed_build.output.properties['which_build'] = 'newer'
+    newer_completed_build.create_time.seconds = 1600000000
+
+    yield (
+        api.test('multiple_completed_builds_uses_most_recent')
+        + current_build()
+        + api.properties(
+            InputProperties(
+                builder=target_builder,
+                enabled=True,
+            )
+        )
+        + search_result(older_completed_build, newer_completed_build)
+        + api.post_check(
+            post_process.MustRun,
+            'reused completed build 6000000000000000000',
+        )
+        + api.post_check(
+            post_process.SummaryMarkdown,
+            'Newer build summary',
+        )
+        + api.post_check(
+            post_process.PropertyEquals,
+            'which_build',
+            'newer',
+        )
+        + api.post_process(post_process.DropExpectation)
+    )