diff --git a/FIREFOX_INTEGRATION.md b/FIREFOX_INTEGRATION.md
index d2da973..289e6fd 100644
--- a/FIREFOX_INTEGRATION.md
+++ b/FIREFOX_INTEGRATION.md
@@ -25,6 +25,23 @@ certificate-error document. It does not yet provide the richer immutable
 `TlsFacts`, append-only journal, plugin chain, policy broker, or fresh retry
 required by the architecture below.
 
+The following commit `e4623c33b3` (*Connect certificate investigation to parent
+trust host*) establishes the first real process boundary. A built-in
+`BrowsecTrustHost.sys.mjs` runs in the Firefox parent process through the
+`NetErrorParent` actor. It validates bounded DER input, computes fingerprints,
+normalizes a Trust API 0.1 failure record, attributes evidence to the Firefox
+TLS adapter, and invokes the irremovable fail-closed final handler. The content
+page now only requests evaluation and renders the returned facts, journal, and
+Boolean verdict. Its browser test passes 11/11 assertions.
+
+This is a host integration slice, not yet the complete TrustLab runner. It has
+one evidence adapter and the built-in final handler; package discovery,
+capability grants, ordered third-party plugins, deadlines, and interactive
+decisions remain to be ported. The input also still travels from trusted
+`about:certerror` to the parent actor. It becomes authoritative only when the
+native PSM continuation freezes and registers the observation before any page
+is created.
+
 ## Pinned reconnaissance baseline
 
 The first source inspection uses an adjacent, shallow Firefox checkout:
diff --git a/SESSION_NOTES.md b/SESSION_NOTES.md
index df2c4b4..fde6a96 100644
--- a/SESSION_NOTES.md
+++ b/SESSION_NOTES.md
@@ -374,3 +374,12 @@ Do not implement distributed trust next. Continue from the Firefox host seam:
   test. The test passes 7/7 assertions. The surface exposes protected Firefox
   failure facts and DER-derived SHA-256 fingerprints but intentionally cannot
   alter trust yet.
+- Firefox commit `e4623c33b3` adds the first parent-process Trust API 0.1 host.
+  `about:certerror` sends its provisional observation through an explicitly
+  allowlisted query; the parent validates bounded DER, computes fingerprints,
+  creates normalized facts, appends attributed adapter evidence, and executes
+  the built-in fail-closed final handler. The page renders the returned record
+  and append-only journal. Its expanded browser test passes 11/11 assertions.
+- This is not yet the complete TrustLab runner or an authoritative native PSM
+  observation. Ordered third-party packages, capabilities, timeouts,
+  interactive decisions, durable policy, and fresh retry remain next.