tractor/ai/prompt-io/claude/20260625T232506Z_3a5cfde0_prompt_io.md

Prompt

Follow-up to a /code-review of PR #460 (this branch) which surfaced lower-severity findings in the .. d2:: sphinx directive. The user’s driving instructions across the session,

yup do both at least, then report back.

(re: “implement #7 (+ optionally #8) on the branch”) and,

well we’re on a clean main so why not just do these now too?

(re: also doing #9). The three findings being addressed,

• #7: a d2 render that is attempted and fails (binary present but errors on the source) silently degraded to the stale committed SVG and the build still exited 0,
• #8: parallel_*_safe = True was declared while run() writes the shared output SVG during the read phase (torn write under sphinx-build -j),
• #9: output keyed only by src.stem so two .d2 sources with the same stem collide.

Response summary

Reworked docs/_ext/d2diagrams.py,

• render_svg() now returns a RenderResult tristate (OK / FELL_BACK / NO_OUTPUT / FAILED) so run() can distinguish a graceful no-binary fallback from a real render failure; FAILED emits a reporter.error (build fails under -W),
• the render writes into a sibling temp-file then os.replace() (atomic) so a failed/torn render can never clobber a good committed SVG,
• a per-build _seen_outputs map (reset on builder-inited) errors on a same-stem output collision.

Verified: a corrupted .d2 errors under -W (exit 1) with the committed SVG byte-unchanged; the collision guard fires on a duplicate stem; nix run nixpkgs#d2 render path + atomic swap leave no temp residue; ruff clean.

Response summary (cont.) — Files changed

• docs/_ext/d2diagrams.py — tristate render result, atomic temp-file render, output-collision guard, doc-string policy update.

Human edits

None — committed as generated (3a5cfde0). The user noted follow-up refinements may come in later commits.