diff --git a/CHANGELOG.d/2.20.1-orchestrator-temperature-negotiation.md b/CHANGELOG.d/2.20.1-orchestrator-temperature-negotiation.md
new file mode 100644
index 000000000..dc05a43e7
--- /dev/null
+++ b/CHANGELOG.d/2.20.1-orchestrator-temperature-negotiation.md
@@ -0,0 +1,7 @@
+# 2.20.1 — Provider temperature capability negotiation
+
+- Compose now pins ContextualWisdomLab/contextual-orchestrator#779 so providers that accept
+  only their default sampling temperature can retry the same request without
+  the unsupported optional field instead of leaving summaries unavailable.
+- The pin remains an immutable upstream commit and does not copy provider
+  behavior or credentials into LineageWeave.
diff --git a/docker/contextual-orchestrator/Dockerfile b/docker/contextual-orchestrator/Dockerfile
index 4e5726543..28eaee190 100644
--- a/docker/contextual-orchestrator/Dockerfile
+++ b/docker/contextual-orchestrator/Dockerfile
@@ -3,10 +3,10 @@ FROM python:3.12-slim@sha256:423ed6ab25b1921a477529254bfeeabf5855151dc2c3141699a
 WORKDIR /app
 
 # Reuse the upstream implementation without copying it into LineageWeave.
-# Pin the runtime to PR #765's pushed commit until that protected PR merges;
+# Pin the runtime to ContextualWisdomLab/contextual-orchestrator#779's pushed commit until that protected PR merges;
 # this keeps model selection, structured synthesis, and reasoning policy in
 # contextual-orchestrator itself.
-ADD https://github.com/ContextualWisdomLab/contextual-orchestrator/archive/7df051a.tar.gz /tmp/contextual-orchestrator.tar.gz
+ADD https://github.com/ContextualWisdomLab/contextual-orchestrator/archive/cf4a4501fa5057f89b21cad5033c5925755cd150.tar.gz /tmp/contextual-orchestrator.tar.gz
 RUN mkdir /tmp/contextual-orchestrator \
     && tar -xzf /tmp/contextual-orchestrator.tar.gz --strip-components=1 -C /tmp/contextual-orchestrator \
     && cp -R /tmp/contextual-orchestrator/contextual_orchestrator /app/contextual_orchestrator \
diff --git a/docs/adr/0083-orchestrator-runtime-commit-pin.md b/docs/adr/0083-orchestrator-runtime-commit-pin.md
index f84cc8230..225032001 100644
--- a/docs/adr/0083-orchestrator-runtime-commit-pin.md
+++ b/docs/adr/0083-orchestrator-runtime-commit-pin.md
@@ -10,14 +10,18 @@ The orchestrator's `auto` reasoning mode is an internal routing decision and
 must not be forwarded as an upstream provider `reasoning_effort` value. The
 runtime also must discover provider models from the configured gateway rather
 than requiring `LLM_GATEWAY_MODEL`, and structured requests must remain
-multi-agent.
+multi-agent. Some provider deployments accept only their default sampling
+temperature; retrying the same rejected value cannot recover that capability
+mismatch.
 
 ## Decision
 
 `docker/contextual-orchestrator/Dockerfile` pins the downloaded archive to
-commit `6db772e`, the pushed head of contextual-orchestrator PR #765. The pin
-remains explicit and immutable until the protected PR merges; it is not a
-moving `main` reference and it is not a LineageWeave monkey patch.
+commit `cf4a4501fa5057f89b21cad5033c5925755cd150`, the pushed head of
+ContextualWisdomLab/contextual-orchestrator#779, stacked on
+ContextualWisdomLab/contextual-orchestrator#765. The pin remains explicit
+and immutable until the protected PRs merge; it is not a moving `main`
+reference and it is not a LineageWeave monkey patch.
 
 The runtime contract is:
 
@@ -33,6 +37,9 @@ The runtime contract is:
   reconciliation prompt; independent VISION worker evidence is retained instead.
 - A provider 4xx is reported as a failed orchestration attempt, never as a
   successful empty semantic result.
+- When HTTP 400/422 explicitly proves that `temperature` is unsupported, the
+  same endpoint is retried once with only that optional field omitted. Invalid
+  values and unrelated 4xx responses remain fail-closed.
 - An empty seed model is expanded from the configured gateway `/v1/models`
   endpoint; embedding-only rows are not added to the chat agent pool.
 - `json_object`, `json_schema`, and Responses JSON formats run conduct plus
@@ -44,4 +51,5 @@ The runtime contract is:
   implementation.
 - Rebuilding the image is required after the upstream pin changes.
 - Protected-branch review and merge remain external gates; this pin does not
-  bypass PR #765.
+  bypass ContextualWisdomLab/contextual-orchestrator#765 or
+  ContextualWisdomLab/contextual-orchestrator#779.
diff --git a/tests/test_orchestrator_runtime_pin.py b/tests/test_orchestrator_runtime_pin.py
new file mode 100644
index 000000000..be37b930c
--- /dev/null
+++ b/tests/test_orchestrator_runtime_pin.py
@@ -0,0 +1,22 @@
+"""Keep the reviewed contextual-orchestrator archive pin and ADR synchronized."""
+
+from pathlib import Path
+
+
+ROOT = Path(__file__).resolve().parents[1]
+ORCHESTRATOR_COMMIT = "cf4a4501fa5057f89b21cad5033c5925755cd150"
+
+
+def test_orchestrator_runtime_pin_matches_adr() -> None:
+    """The image and decision record must identify the same immutable commit."""
+    dockerfile = (ROOT / "docker/contextual-orchestrator/Dockerfile").read_text(
+        encoding="utf-8"
+    )
+    adr = (ROOT / "docs/adr/0083-orchestrator-runtime-commit-pin.md").read_text(
+        encoding="utf-8"
+    )
+
+    assert f"contextual-orchestrator/archive/{ORCHESTRATOR_COMMIT}.tar.gz" in dockerfile
+    assert f"commit `{ORCHESTRATOR_COMMIT}`" in adr
+    upstream_pr = "ContextualWisdomLab/contextual-orchestrator#779"
+    assert upstream_pr in dockerfile and upstream_pr in adr