fix: make daily task log header-only

.project-docs/50-evidence/topics/2026-08-11-0806-xml-invalid-utf8.md

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+# `0806.XML` invalid UTF-8 diagnosis
+
+## Metadata
+
+- Date: 2026-08-11
+- Status: Read-only input diagnosis; source re-export required
+- Scope: exact desktop `0806.XML`, processor 4.0.0 isolated replay, public deployment health probe
+- Confidence: High for the inspected file; the authenticated remote artifact hash was not read
+
+## Observed behavior
+
+- The public ARR endpoint at `8.138.234.141:8765` remained healthy: anonymous `/healthz` returned HTTP 200 while
+  authenticated detail endpoints remained protected.
+- The inspected `0806.XML` is 694,286 bytes with SHA-256
+  `b41c103bfad7f9f0abb25af159a0c5920f0f9b89e156d31919521d057b62639f`.
+- An isolated active-processor replay exited 3 with `status=failed`, `business_date=null`, zero parsed source rows and
+  exactly one `XML_PARSE_ERROR`: `not well-formed (invalid token): line 1872, column 0`.
+- The structured result is processor 4.0.0 / Schema 4.0 with `activation_eligible=false`; every outcome count and
+  review count is zero. No price matching was reached.
+
+## Root cause
+
+- The XML declaration says UTF-8, but line 1872 inside a `TRACE_TEXT` value begins with bytes
+  `ED A0 BC ED BE 89`.
+- Those six bytes are the CESU-8 representation of UTF-16 surrogate pair `U+D83C U+DF89`, whose intended Unicode
+  scalar is `U+1F389`. UTF-8 must encode that scalar as one four-byte sequence; XML 1.0 also forbids surrogate code
+  points as PCDATA.
+- The file contains exactly one such surrogate pair. Its closing XML structure is present, so this is an encoding
+  defect rather than a truncated export.
+- Manual price review is intentionally unavailable: only a non-empty error set consisting entirely of
+  `PRICE_UNMATCHED` can enter `review_required`; `XML_PARSE_ERROR` is a formal input failure before pricing.
+
+## Safe recovery boundary
+
+Re-export the 2026-08-06 Opera XML as standards-compliant UTF-8, preferably after the upstream trace text no longer
+contains the mis-encoded character, then upload the new export as a fresh task. Do not edit the registered source
+artifact or convert the failed task into a review case. A fresh replay is still required to discover any later price
+or business-rule issues after parsing succeeds.
+
+No original XML byte, upload, review item, database fact, Finance version, object-store object, event or runtime process
+was changed during this diagnosis.