diff --git a/docs/hackbot/tracing.md b/docs/hackbot/tracing.md
index a7ebe630a1..92ba80fbe1 100644
--- a/docs/hackbot/tracing.md
+++ b/docs/hackbot/tracing.md
@@ -13,6 +13,15 @@ It is **opt-in**: the runtime only traces when it has W&B credentials, and never
 fails a run if Weave can't start. `WEAVE_PROJECT` picks the destination project
 (a bare `project` or `entity/project`; defaults to `hackbot-test`).
 
+## Linking a run to its traces
+
+The runtime tags every span with the hackbot run id (surfaced by Weave as
+`attributes.hackbot.run_id`, see [tracing.py](../../libs/hackbot-runtime/hackbot_runtime/tracing.py)).
+The Hackbot UI links each run page to the Weave **Agents** view filtered on that
+attribute, so all of a run's conversations show up together. The UI's
+`WEAVE_PROJECT` (`entity/project`, default `moz-bugbug/hackbot-dev`) must point at
+the project the agents trace into.
+
 **Locally**, add the key to your root `.env`; the agent's `compose.yml` should
 pass `WANDB_API_KEY` through to the agent container.
 
diff --git a/libs/hackbot-runtime/hackbot_runtime/runtime.py b/libs/hackbot-runtime/hackbot_runtime/runtime.py
index 7b926e5fd7..30af26eea0 100644
--- a/libs/hackbot-runtime/hackbot_runtime/runtime.py
+++ b/libs/hackbot-runtime/hackbot_runtime/runtime.py
@@ -193,7 +193,7 @@ def run(entrypoint: AgentMain, config: ConfigArg = None) -> NoReturn:
 
     try:
         _configure_auth()
-        with trace_agent(entrypoint):
+        with trace_agent(entrypoint, ctx.run_id):
             outcome: object = entrypoint(ctx)
     except Exception as exc:
         log.exception("Agent raised an exception")
@@ -210,7 +210,7 @@ def run_async(entrypoint: AsyncAgentMain, config: ConfigArg = None) -> NoReturn:
 
     try:
         _configure_auth()
-        with trace_agent(entrypoint):
+        with trace_agent(entrypoint, ctx.run_id):
             outcome: object = asyncio.run(entrypoint(ctx))
     except Exception as exc:
         log.exception("Agent raised an exception")
diff --git a/libs/hackbot-runtime/hackbot_runtime/tracing.py b/libs/hackbot-runtime/hackbot_runtime/tracing.py
index 83ba0f71bd..4691148146 100644
--- a/libs/hackbot-runtime/hackbot_runtime/tracing.py
+++ b/libs/hackbot-runtime/hackbot_runtime/tracing.py
@@ -19,15 +19,27 @@
 import os
 from collections.abc import Callable, Iterator
 from pathlib import Path
+from typing import TYPE_CHECKING
+
+from opentelemetry import trace as otel_trace
+from opentelemetry.sdk.trace import SpanProcessor, TracerProvider
 
 from hackbot_runtime import wandb_wif
 
+if TYPE_CHECKING:
+    from opentelemetry.context import Context
+    from opentelemetry.sdk.trace import Span
+
 log = logging.getLogger("hackbot_runtime")
 
 # Weave project traces land in when the deploy doesn't set WEAVE_PROJECT. Accepts
 # either "project" or "entity/project".
 DEFAULT_WEAVE_PROJECT = "hackbot-test"
 
+# Weave's tagging namespace: the server surfaces this as `attributes.hackbot.run_id`
+# on every call, which the Hackbot UI uses to link a run to its traces.
+RUN_ID_SPAN_ATTRIBUTE = "wandb.attributes.hackbot.run_id"
+
 
 def resolve_agent_name(entrypoint: Callable) -> str:
     """The running agent's name, derived from its ``main()`` source file.
@@ -64,9 +76,23 @@ def _init_weave() -> bool:
         return False
 
 
+class _RunIdSpanProcessor(SpanProcessor):
+    def __init__(self, run_id: str) -> None:
+        self._run_id = run_id
+
+    def on_start(self, span: "Span", parent_context: "Context | None" = None) -> None:
+        span.set_attribute(RUN_ID_SPAN_ATTRIBUTE, self._run_id)
+
+
+def _tag_spans_with_run_id(run_id: str) -> None:
+    provider = otel_trace.get_tracer_provider()
+    if isinstance(provider, TracerProvider):
+        provider.add_span_processor(_RunIdSpanProcessor(run_id))
+
+
 @contextlib.contextmanager
-def trace_agent(entrypoint: Callable) -> Iterator[None]:
-    """Trace the agent run and label its Weave spans with the agent's name.
+def trace_agent(entrypoint: Callable, run_id: str) -> Iterator[None]:
+    """Trace the agent run, labelled with the agent's name and tagged with the run id.
 
     A no-op when tracing isn't configured (no W&B credentials).
     """
@@ -76,6 +102,7 @@ def trace_agent(entrypoint: Callable) -> Iterator[None]:
 
     from weave.conversation import agent_name_override
 
+    _tag_spans_with_run_id(run_id)
     agent = resolve_agent_name(entrypoint)
     log.info("Enabled Weave tracing for agent %s", agent)
     with agent_name_override(agent):
diff --git a/libs/hackbot-runtime/tests/test_tracing.py b/libs/hackbot-runtime/tests/test_tracing.py
index 4a1bee7135..f777c881a7 100644
--- a/libs/hackbot-runtime/tests/test_tracing.py
+++ b/libs/hackbot-runtime/tests/test_tracing.py
@@ -2,6 +2,7 @@
 
 import pytest
 from hackbot_runtime import tracing, wandb_wif
+from opentelemetry.sdk.trace import TracerProvider
 from weave.conversation.agent_context import resolve_agent_name as weave_agent_name
 
 
@@ -69,7 +70,7 @@ def test_init_weave_enabled_by_wif_token_file(monkeypatch):
 
 def test_trace_agent_is_noop_without_credentials():
     entry = _entrypoint_at("/app/hackbot_agents/build_repair/__main__.py")
-    with tracing.trace_agent(entry):
+    with tracing.trace_agent(entry, "run-1"):
         assert weave_agent_name("claude_agent_sdk") == "claude_agent_sdk"
 
 
@@ -77,6 +78,28 @@ def test_trace_agent_labels_spans_when_enabled(monkeypatch):
     monkeypatch.setattr(tracing, "_init_weave", lambda: True)
     entry = _entrypoint_at("/app/hackbot_agents/build_repair/__main__.py")
 
-    with tracing.trace_agent(entry):
+    with tracing.trace_agent(entry, "run-1"):
         assert weave_agent_name("claude_agent_sdk") == "build-repair"
     assert weave_agent_name("claude_agent_sdk") == "claude_agent_sdk"
+
+
+def test_trace_agent_tags_spans_with_run_id(monkeypatch):
+    monkeypatch.setattr(tracing, "_init_weave", lambda: True)
+    provider = TracerProvider()
+    monkeypatch.setattr(tracing.otel_trace, "get_tracer_provider", lambda: provider)
+    entry = _entrypoint_at("/app/hackbot_agents/build_repair/__main__.py")
+
+    with tracing.trace_agent(entry, "run-1"):
+        with provider.get_tracer("test").start_as_current_span("turn") as span:
+            pass
+
+    assert span.attributes[tracing.RUN_ID_SPAN_ATTRIBUTE] == "run-1"
+
+
+def test_trace_agent_skips_tagging_without_sdk_provider(monkeypatch):
+    monkeypatch.setattr(tracing, "_init_weave", lambda: True)
+    monkeypatch.setattr(tracing.otel_trace, "get_tracer_provider", lambda: object())
+    entry = _entrypoint_at("/app/hackbot_agents/build_repair/__main__.py")
+
+    with tracing.trace_agent(entry, "run-1"):
+        pass
diff --git a/services/hackbot-ui/.env.example b/services/hackbot-ui/.env.example
index 560468e4e7..906208ae32 100644
--- a/services/hackbot-ui/.env.example
+++ b/services/hackbot-ui/.env.example
@@ -5,6 +5,9 @@ HACKBOT_API_URL=http://localhost:8080
 # EXTERNAL_API_KEY. Stays server-side — it is never shipped to the browser.
 HACKBOT_API_KEY=
 
+# Weave project (entity/project) the agents trace into; the run page links there.
+WEAVE_PROJECT=moz-bugbug/hackbot-dev
+
 # Public base URL of THIS web app, used by better-auth for callbacks.
 BETTER_AUTH_URL=http://localhost:3000
 
diff --git a/services/hackbot-ui/README.md b/services/hackbot-ui/README.md
index c14c2d4828..a22d87f5f7 100644
--- a/services/hackbot-ui/README.md
+++ b/services/hackbot-ui/README.md
@@ -132,6 +132,7 @@ must match its `X-API-Key`.
 | ---------------------- | -------------------------------------------------- |
 | `HACKBOT_API_URL`      | Base URL of hackbot-api (no trailing slash)        |
 | `HACKBOT_API_KEY`      | Value for the `X-API-Key` header (server-side)     |
+| `WEAVE_PROJECT`        | Weave `entity/project` for run trace links         |
 | `BETTER_AUTH_URL`      | Public base URL of this app                        |
 | `BETTER_AUTH_SECRET`   | Session signing secret (`openssl rand -base64 32`) |
 | `GOOGLE_CLIENT_ID`     | Google OAuth client ID                             |
diff --git a/services/hackbot-ui/app/runs/[runId]/page.tsx b/services/hackbot-ui/app/runs/[runId]/page.tsx
index 244da0dbd5..c85a56569f 100644
--- a/services/hackbot-ui/app/runs/[runId]/page.tsx
+++ b/services/hackbot-ui/app/runs/[runId]/page.tsx
@@ -1,4 +1,5 @@
 import { RunDetail } from "@/components/RunDetail";
+import { weaveProject, weaveRunTracesUrl } from "@/lib/weave";
 
 export default async function RunPage({
   params,
@@ -7,5 +8,11 @@ export default async function RunPage({
 }) {
   const { runId } = await params;
 
-  return <RunDetail key={runId} runId={runId} />;
+  return (
+    <RunDetail
+      key={runId}
+      runId={runId}
+      tracesUrl={weaveRunTracesUrl(weaveProject(), runId)}
+    />
+  );
 }
diff --git a/services/hackbot-ui/components/RunDetail.tsx b/services/hackbot-ui/components/RunDetail.tsx
index 64dc77779a..7f9935f6a8 100644
--- a/services/hackbot-ui/components/RunDetail.tsx
+++ b/services/hackbot-ui/components/RunDetail.tsx
@@ -53,7 +53,13 @@ function extractLog(run: RunDoc): string | null {
   return null;
 }
 
-export function RunDetail({ runId }: { runId: string }) {
+export function RunDetail({
+  runId,
+  tracesUrl,
+}: {
+  runId: string;
+  tracesUrl: string;
+}) {
   const router = useRouter();
   const [run, setRun] = useState<RunDoc | null>(null);
   const [error, setError] = useState<string | null>(null);
@@ -232,6 +238,12 @@ export function RunDetail({ runId }: { runId: string }) {
               <dd>{run.execution_name}</dd>
             </>
           )}
+          <dt>Traces</dt>
+          <dd>
+            <a href={tracesUrl} target="_blank" rel="noreferrer">
+              Weave
+            </a>
+          </dd>
         </dl>
         <button
           type="button"
diff --git a/services/hackbot-ui/deploy.sh b/services/hackbot-ui/deploy.sh
index f7b23ad928..2e5b505573 100755
--- a/services/hackbot-ui/deploy.sh
+++ b/services/hackbot-ui/deploy.sh
@@ -75,6 +75,7 @@ gcloud builds submit "${SCRIPT_DIR}" --tag "${IMAGE}"
 echo "==> Deploying to Cloud Run"
 ENV_VARS="HACKBOT_API_URL=${HACKBOT_API_URL},GOOGLE_CLIENT_ID=${GOOGLE_CLIENT_ID}"
 [ -n "${BETTER_AUTH_URL}" ] && ENV_VARS="${ENV_VARS},BETTER_AUTH_URL=${BETTER_AUTH_URL}"
+[ -n "${WEAVE_PROJECT:-}" ] && ENV_VARS="${ENV_VARS},WEAVE_PROJECT=${WEAVE_PROJECT}"
 
 gcloud run deploy "${SERVICE}" \
   --image "${IMAGE}" \
diff --git a/services/hackbot-ui/lib/weave.test.ts b/services/hackbot-ui/lib/weave.test.ts
new file mode 100644
index 0000000000..ef3522c998
--- /dev/null
+++ b/services/hackbot-ui/lib/weave.test.ts
@@ -0,0 +1,12 @@
+import assert from "node:assert/strict";
+import { test } from "node:test";
+
+import { weaveRunTracesUrl } from "./weave.ts";
+
+test("links to the agents view filtered by run id", () => {
+  assert.equal(
+    weaveRunTracesUrl("moz-bugbug/hackbot-dev", "local-20260910-182751-1f1633"),
+    "https://wandb.ai/moz-bugbug/hackbot-dev/weave/agents/conversations" +
+      "?filters[custom_attrs_string:wandb.attributes.hackbot.run_id]=local-20260910-182751-1f1633"
+  );
+});
diff --git a/services/hackbot-ui/lib/weave.ts b/services/hackbot-ui/lib/weave.ts
new file mode 100644
index 0000000000..bb3d72ea6f
--- /dev/null
+++ b/services/hackbot-ui/lib/weave.ts
@@ -0,0 +1,15 @@
+const DEFAULT_WEAVE_PROJECT = "moz-bugbug/hackbot-dev";
+
+// Weave project ("entity/project") the agents trace into; server-side only.
+export function weaveProject(): string {
+  return process.env.WEAVE_PROJECT || DEFAULT_WEAVE_PROJECT;
+}
+
+// Weave Agents view filtered to the conversations tagged with this run id
+// (hackbot-runtime stamps it on every span as attributes.hackbot.run_id).
+export function weaveRunTracesUrl(project: string, runId: string): string {
+  return (
+    `https://wandb.ai/${project}/weave/agents/conversations` +
+    `?filters[custom_attrs_string:wandb.attributes.hackbot.run_id]=${encodeURIComponent(runId)}`
+  );
+}