Record the remaining file buffer cleanup issue

docs/roadmap/remediation.md

@@ -1,6 +1,51 @@
 # Implementation Review Remediation
 
-Status: All recorded findings have been resolved in separate remediation units.
+Status: One computational-efficiency finding awaits remediation. Earlier
+findings below remain resolved.
+
+## Computational Efficiency Review
+
+Review baseline: `8a5c0de`, compared with planning commit `3fde1f6`, the
+[performance roadmap](performance.md), and [implementation plan](implementation.md).
+
+### Finding 1 — Release A Stale File Reservation For An Empty Body (P3)
+
+**Status: Open.**
+
+Location: [file reader](../../internal/artifact/reader.go), lines 137–166.
+
+The new file-size reservation is compacted only when the completed body is
+nonempty. If the opened file reports a positive size but yields no bytes
+(for example, because it is truncated before the read), the empty artifact
+retains the entire reservation. An offline diagnostic using the existing
+opened-file test seam reported a 16 MiB size and returned immediate EOF:
+the result had zero body bytes and size zero, but retained a 1 MiB backing
+array. The previous reader did not reserve that storage for an empty result.
+
+This is a retained-memory edge case, not incorrect content, a permanent leak,
+or a problem with ordinary empty files whose size hint is zero. It leaves
+Stage 4's stale-hint cleanup incomplete.
+
+Remediation: release the reserved backing storage when the completed body is
+empty, preserving existing empty-artifact semantics. Keep size and hash based
+on the actual body, and retain the existing EOF and cancellation behavior.
+No new input limit or public capacity guarantee is needed.
+
+Verification: extend the stale-size cases to include an empty actual file
+with a positive reported size; check accepted content, metadata, and hash.
+Use a focused retained-memory diagnostic or benchmark to verify that the
+reservation is released, rather than making an exact capacity or allocation
+count a durable test requirement.
+
+Also correct the accompanying wording in
+[Ordinary Artifacts](../internal/sources.md#ordinary-artifacts): the current
+predicate compacts when unused capacity exceeds the body length (total
+capacity exceeds twice the body length), not when unused capacity exceeds
+twice the body length.
+
+Review verification: the complete offline race suite, repository-wide Go vet,
+and maintained consumer examples passed. No additional actionable architecture
+gaps or strengthened public contracts were identified in this review.
 
 ## Effective Requirement Inspection Review