Release validation source bytes after checks

docs/internal/validation.md

@@ -52,8 +52,11 @@ must close it when finished. The shared validation executor closes its tree on
 every return before product checks or build callbacks run. A metadata-only
 selection never starts the reader. Per-read contexts cancel an in-flight blob
 exchange without tying the reader lifetime to a short-lived caller context.
-Until formatting and parsed-result reuse are in place, regular-file bytes stay
-cached by object ID for the lifetime of the tree.
+Regular-file reads return independent caller-owned byte slices and are not
+retained by the tree. Symlink targets are retained as immutable owned strings
+by blob object ID; explicitly reading a symlink still returns independent
+bytes. The Go-format check caches only whether each successfully inspected
+object is formatted, then reports every unformatted path that refers to it.
 
 The internal Markdown parser uses Goldmark to record inline, reference, and
 autolinks, images, titles, and their source use sites, and to build heading

docs/roadmap/implementation.md

@@ -1,6 +1,6 @@
 # Computational Efficiency Implementation Plan
 
-**Status:** Stages 1–5 complete; Stages 6–11 pending.
+**Status:** Stages 1–6 complete; Stages 7–11 pending.
 
 ## Purpose And Baseline
 
@@ -359,6 +359,22 @@ buffers after formatting, and duplicate-content files retain per-path findings.
 Record the tradeoff for explicit repeated raw reads. Update validation mechanics
 with the new ownership and reuse choices.
 
+**Completion:** Complete. Regular-file reads now return independent bytes and
+are not retained by `CandidateTree`; repeated explicit reads therefore transfer
+the blob again. The tree caches owned symlink-target strings by object ID, and
+explicit symlink reads still return independent byte slices. Go formatting
+caches only successful formatted/unformatted outcomes by object ID, checks
+cancellation per path, and reports every unformatted path even when contents
+repeat. Validation tests and the formatting/Markdown destination benchmarks
+passed. On the same Go 1.26.8, Git 2.53.0, Linux x86_64 Intel Core i5-7260U
+setup, three repetitions measured unique-file formatting at 75.0–75.9 ms loose
+and 37.9–42.5 ms packed, repeated-ID formatting at 1.97–2.17 ms, and the
+Markdown workload at 16.3–17.0 ms. Formatting used about 2.89 MB/op for unique
+files and 121 KB/op for repeated IDs. The retained-memory observation was
+129,496 bytes with the candidate and Markdown cache alive, compared with
+1,385,040–1,385,616 bytes in the baseline fixture. This retains Markdown parser
+data by path until Stage 7; it is a workload-specific heap observation.
+
 ## Stage 7: Reuse Owned Markdown And Module Results
 
 **Owners:** [markdown.go](../../internal/validation/markdown.go),