diff --git a/factory/scripts/container-entrypoint.sh b/factory/scripts/container-entrypoint.sh
index bf108e6..49b834e 100755
--- a/factory/scripts/container-entrypoint.sh
+++ b/factory/scripts/container-entrypoint.sh
@@ -13,18 +13,48 @@ test -r "$INPUT_ROOT/catalog.json"
 test -r "$REPO_ROOT/factory/coordinator.md"
 rm -rf "$WORKSPACE_ROOT"
 mkdir -p "$WORKSPACE_ROOT/.factory" "$KIT_HOME" "$EXPORT_ROOT"
-rm -rf "$EXPORT_ROOT/guide" "$EXPORT_ROOT/run-report.json"
+rm -rf "$EXPORT_ROOT/guide" "$EXPORT_ROOT/run-report.json" "$EXPORT_ROOT/kit-error-summary.json"
 cp -a "$REPO_ROOT/." "$WORKSPACE_ROOT/"
 rm -rf "$WORKSPACE_ROOT/.git"
 export HOME="$KIT_HOME"
 KIT_BIN=${KIT_BIN:-kit}
-"$KIT_BIN" prompt \
+if ! "$KIT_BIN" prompt \
   --root "$WORKSPACE_ROOT" \
   --provider openrouter \
   --model "$KIT_MODEL" \
   --reasoning-effort "$KIT_REASONING_EFFORT" \
   --mcp-config "$WORKSPACE_ROOT/factory/mcp/exa.json" \
-  "$(cat "$WORKSPACE_ROOT/factory/coordinator.md")"
+  "$(cat "$WORKSPACE_ROOT/factory/coordinator.md")"; then
+  error_files=()
+  while IFS= read -r error_file; do
+    error_files+=("$error_file")
+  done < <(find "$KIT_HOME/errors" -type f -name '*.json' -print 2>/dev/null || true)
+  if (( ${#error_files[@]} == 0 )); then
+    jq -n '{schema_version:1,records:[]}' >"$EXPORT_ROOT/kit-error-summary.json"
+  else
+    jq -s '
+      {schema_version:1,records:[.[] | {
+        schema_version,kind,code,
+        diagnostics:(if (.diagnostics | type) == "object" then {
+          stage:.diagnostics.stage,
+          retryable:.diagnostics.retryable,
+          attempt:.diagnostics.attempt,
+          response_request_id:(.diagnostics.response_request_id // null),
+          reqwest:{
+            timeout:.diagnostics.reqwest.timeout,
+            connect:.diagnostics.reqwest.connect,
+            request:.diagnostics.reqwest.request,
+            body:.diagnostics.reqwest.body,
+            decode:.diagnostics.reqwest.decode
+          },
+          source_chain_unknown:.diagnostics.source_chain_unknown,
+          source_chain_truncated:.diagnostics.source_chain_truncated
+        } else null end)
+      }]}
+    ' "${error_files[@]}" >"$EXPORT_ROOT/kit-error-summary.json"
+  fi
+  exit 1
+fi
 test -s "$WORKSPACE_ROOT/.factory/run-report.json"
 "$REPORT_VALIDATOR" "$WORKSPACE_ROOT/.factory/run-report.json"
 outcome="$(jq -r '.outcome' "$WORKSPACE_ROOT/.factory/run-report.json")"
diff --git a/factory/scripts/run-kit.sh b/factory/scripts/run-kit.sh
index efc69b8..c51d265 100755
--- a/factory/scripts/run-kit.sh
+++ b/factory/scripts/run-kit.sh
@@ -21,7 +21,7 @@ issue_json="$(realpath "$issue_json")"
 catalog_json="$(realpath "$catalog_json")"
 mkdir -p "$export_dir"
 export_dir="$(realpath "$export_dir")"
-rm -rf "$export_dir/guide" "$export_dir/run-report.json"
+rm -rf "$export_dir/guide" "$export_dir/run-report.json" "$export_dir/kit-error-summary.json"
 
 source_snapshot="$(mktemp -d "${TMPDIR:-/tmp}/mcp-setup-docs-source.XXXXXX")"
 source_snapshot="$(realpath "$source_snapshot")"
@@ -43,7 +43,7 @@ tar -cf - --exclude-from="$ROOT/.dockerignore" -C "$ROOT" . \
   --tag "$KIT_IMAGE" \
   "$ROOT"
 
-"$FACTORY_DOCKER" run --rm \
+if ! "$FACTORY_DOCKER" run --rm \
   --env OPENROUTER_API_KEY \
   --env "KIT_MODEL=$KIT_MODEL" \
   --env "KIT_REASONING_EFFORT=$KIT_REASONING_EFFORT" \
@@ -51,4 +51,34 @@ tar -cf - --exclude-from="$ROOT/.dockerignore" -C "$ROOT" . \
   --volume "$issue_json:/input/issue.json:ro" \
   --volume "$catalog_json:/input/catalog.json:ro" \
   --volume "$export_dir:/export" \
-  "$KIT_IMAGE"
+  "$KIT_IMAGE"; then
+  if [[ -f "$export_dir/kit-error-summary.json" ]] && jq -e '
+    (keys | sort) == (["records","schema_version"] | sort)
+    and .schema_version == 1
+    and (.records | type) == "array"
+    and all(.records[];
+      (keys | sort) == (["code","diagnostics","kind","schema_version"] | sort)
+      and .schema_version == 2
+      and (.kind | type) == "string" and (.kind | test("^[a-z0-9_]{1,64}$"))
+      and (.code | type) == "string" and (.code | test("^[a-z0-9_]{1,64}$"))
+      and (.diagnostics == null or (
+        (.diagnostics | type) == "object"
+        and (.diagnostics | keys | sort) == (["attempt","reqwest","response_request_id","retryable","source_chain_truncated","source_chain_unknown","stage"] | sort)
+        and (.diagnostics.stage | IN("request","stream"))
+        and (.diagnostics.retryable | type) == "boolean"
+        and (.diagnostics.attempt | type) == "number" and (.diagnostics.attempt | floor) == .diagnostics.attempt
+        and (.diagnostics.attempt >= 1 and .diagnostics.attempt <= 1000)
+        and (.diagnostics.response_request_id == null or (
+          (.diagnostics.response_request_id | type) == "string"
+          and (.diagnostics.response_request_id | test("^[A-Za-z0-9_.:-]{1,128}$"))))
+        and (.diagnostics.reqwest | keys | sort) == (["body","connect","decode","request","timeout"] | sort)
+        and all(.diagnostics.reqwest[]; type == "boolean")
+        and (.diagnostics.source_chain_unknown | type) == "boolean"
+        and (.diagnostics.source_chain_truncated | type) == "boolean"
+      )))
+  ' "$export_dir/kit-error-summary.json" >/dev/null; then
+    printf 'factory: Kit failure diagnostic: ' >&2
+    jq -c . "$export_dir/kit-error-summary.json" >&2
+  fi
+  exit 1
+fi
diff --git a/factory/tests/test-container.sh b/factory/tests/test-container.sh
index 5c806a2..36f6a45 100755
--- a/factory/tests/test-container.sh
+++ b/factory/tests/test-container.sh
@@ -105,6 +105,39 @@ test_run_kit_does_not_forward_github_credentials() {
   ! grep -qE 'GH_TOKEN|SSH_AUTH_SOCK' "$TMP/docker.args"
 }
 
+test_run_kit_reports_safe_failure_diagnostics() {
+  export OPENROUTER_API_KEY=or-test FACTORY_DOCKER="$TMP/bin/docker"
+  # shellcheck disable=SC2016
+  make_fake docker '[[ "${1:-}" == build ]] && exit 0; mkdir -p "$TMP/error-run-export"; printf '"'"'{"schema_version":1,"records":[{"schema_version":2,"kind":"provider","code":"provider_error","diagnostics":null}]}\n'"'"' >"$TMP/error-run-export/kit-error-summary.json"; exit 1'
+  printf '{}\n' >"$TMP/issue.json"; printf '{}\n' >"$TMP/catalog.json"
+  if "$ROOT/factory/scripts/run-kit.sh" "$TMP/issue.json" "$TMP/catalog.json" "$TMP/error-run-export" \
+    >"$TMP/out" 2>"$TMP/err"; then
+    fail 'run-kit accepted failed container'
+  fi
+  assert_contains '"code":"provider_error"' "$(cat "$TMP/err")"
+
+  # shellcheck disable=SC2016
+  make_fake docker '[[ "${1:-}" == build ]] && exit 0; mkdir -p "$TMP/error-run-export"; printf '"'"'{"schema_version":1,"records":[{"schema_version":2,"kind":"provider","code":"provider_error","diagnostics":{"stage":"request","retryable":false,"attempt":1,"response_request_id":null,"reqwest":{"timeout":false,"connect":false,"request":false,"body":false,"decode":false},"source_chain_unknown":false,"source_chain_truncated":false,"provider_body":"sensitive-nested-diagnostic"}}]}\n'"'"' >"$TMP/error-run-export/kit-error-summary.json"; exit 1'
+  if "$ROOT/factory/scripts/run-kit.sh" "$TMP/issue.json" "$TMP/catalog.json" "$TMP/error-run-export" \
+    >"$TMP/out" 2>"$TMP/err"; then
+    fail 'run-kit accepted malicious diagnostics'
+  fi
+  if grep -q 'sensitive-nested-diagnostic' "$TMP/err"; then
+    fail 'run-kit logged unvalidated nested diagnostics'
+  fi
+
+  printf '%s\n' 'sensitive-stale-diagnostic' >"$TMP/error-run-export/kit-error-summary.json"
+  make_fake docker 'exit 1'
+  if "$ROOT/factory/scripts/run-kit.sh" "$TMP/issue.json" "$TMP/catalog.json" "$TMP/error-run-export" \
+    >"$TMP/out" 2>"$TMP/err"; then
+    fail 'run-kit accepted failed build'
+  fi
+  test ! -e "$TMP/error-run-export/kit-error-summary.json"
+  if grep -q 'sensitive-stale-diagnostic' "$TMP/err"; then
+    fail 'run-kit logged stale diagnostics'
+  fi
+}
+
 test_run_kit_uses_only_allowed_mounts() {
   export OPENROUTER_API_KEY=or-test
   export FACTORY_DOCKER="$TMP/bin/docker"
@@ -281,6 +314,46 @@ MOCK
   done
 }
 
+test_entrypoint_exports_safe_kit_failure_diagnostics() {
+  local repo input workspace export_root fake_kit
+  repo="$TMP/error-repo"; input="$TMP/error-input"
+  workspace="$TMP/error-workspace"; export_root="$TMP/error-export"
+  fake_kit="$TMP/bin/error-kit"
+  mkdir -p "$repo/factory" "$input" "$TMP/bin"
+  printf 'assignment\n' >"$repo/factory/coordinator.md"
+  printf '{}\n' >"$input/issue.json"; printf '{}\n' >"$input/catalog.json"
+  cat >"$fake_kit" <<'MOCK'
+#!/usr/bin/env bash
+mkdir -p "$HOME/errors/s-test"
+cat >"$HOME/errors/s-test/e-test.json" <<'JSON'
+{"schema_version":2,"event_id":"e-test","occurred_at_ms":1,"kit_version":"0.1.98","session_id":"s-test","surface":"prompt","kind":"provider","code":"provider_error","message":"sensitive-provider-body","prompt":{"code":"sensitive-code","provider":"sensitive-provider"},"url":"https://sensitive.example","diagnostics":null}
+JSON
+cat >"$HOME/errors/s-test/e-transport.json" <<'JSON'
+{"schema_version":2,"event_id":"e-transport","occurred_at_ms":2,"kit_version":"0.1.98","session_id":"s-test","surface":"prompt","kind":"provider","code":"request_transport","message":"sensitive-transport-message","diagnostics":{"stage":"request","retryable":true,"attempt":2,"response_request_id":"req_safe-123","reqwest":{"timeout":false,"connect":true,"request":true,"body":false,"decode":false},"source_chain":[{"code":"sensitive-source-code","provider":"sensitive-source-provider"}],"source_chain_unknown":true,"source_chain_truncated":false}}
+JSON
+exit 1
+MOCK
+  chmod +x "$fake_kit"
+  if FACTORY_REPO_ROOT="$repo" FACTORY_INPUT_ROOT="$input" \
+    FACTORY_WORKSPACE_ROOT="$workspace" FACTORY_EXPORT_ROOT="$export_root" \
+    FACTORY_KIT_HOME="$TMP/error-home" KIT_BIN="$fake_kit" \
+    FACTORY_REPORT_VALIDATOR="$ROOT/factory/scripts/validate-report.sh" \
+    KIT_MODEL=openai/gpt-5.6-sol KIT_REASONING_EFFORT=high \
+    "$ROOT/factory/scripts/container-entrypoint.sh" >/dev/null 2>&1; then
+    fail 'entrypoint accepted failed Kit process'
+  fi
+  jq -e '
+    (.records | length) == 2
+    and any(.records[]; .kind == "provider" and .code == "provider_error" and .diagnostics == null)
+    and any(.records[];
+      .code == "request_transport"
+      and .diagnostics == {stage:"request",retryable:true,attempt:2,response_request_id:"req_safe-123",reqwest:{timeout:false,connect:true,request:true,body:false,decode:false},source_chain_unknown:true,source_chain_truncated:false})
+  ' "$export_root/kit-error-summary.json" >/dev/null
+  if grep -Eq 'sensitive-provider-body|sensitive-code|sensitive-provider|sensitive-transport-message|sensitive-source|sensitive\.example' "$export_root/kit-error-summary.json"; then
+    fail 'Kit failure diagnostics leaked unsafe fields'
+  fi
+}
+
 test_local_draft_parsing_and_secret_boundary() {
   local bin log tmpdir issue_path
   bin="$TMP/local-bin"; log="$TMP/local.log"; tmpdir="$TMP/local tmp"
@@ -380,10 +453,12 @@ test_dockerfile_builds_static_linter_without_go_in_final_image
 test_docker_context_excludes_credentials_and_keeps_build_inputs
 test_release_archive_layout_and_checksum
 test_run_kit_does_not_forward_github_credentials
+test_run_kit_reports_safe_failure_diagnostics
 test_run_kit_uses_only_allowed_mounts
 test_run_kit_source_snapshot_applies_dockerignore
 test_entrypoint_exports_only_selected_guide_with_mocked_kit
 test_entrypoint_rejects_invalid_report
+test_entrypoint_exports_safe_kit_failure_diagnostics
 test_local_draft_parsing_and_secret_boundary
 test_local_draft_rejects_invalid_arguments_and_slug_mismatch
 test_opt_in_final_image