Phase 8: Graphviz coverage expansion (easy wins)

[exactmike]

Summary

Reviews Graphviz's own documentation (graphviz.org's attribute/shape references, the Graphviz CHANGELOG, forum.graphviz.org) against PSGraph's current surface and closes the convenience/discoverability gaps that turned up, reusing the module's existing attribute-set-builder pattern rather than adding new machinery. Every DSL keyword already accepts a generic -Attributes hashtable passthrough, so none of this is about raw capability — it's about ValidateSets that reject valid Graphviz values, and attributes with no dedicated parameter anywhere.

• Export-PSGraph -OutputFormat: widened from 10 to 26 accepted formats (svgz, svg_inline, eps, ps, ps2, xdot, dot_json, xdot_json, json0, canon, gv, fig, bmp, tif/tiff, wbmp, pic, plain-ext) — the old list rejected several valid dot -T values outright. List validated against a real dot -T? on the dev machine (Graphviz 15.1.1); two originally-planned formats (vml/vmlz) turned out not to exist in current Graphviz builds and were swapped for json0/plain-ext.
• Export-PSGraph -LayoutEngine: added osage and patchwork, the two Graphviz layout engines that were previously unreachable.
• Graph -Strict: new switch, emits strict digraph/strict graph so GraphViz merges duplicate edges.
• New-GraphAttributeSet (alias GraphAttributes): new graph/cluster-level attribute-set builder mirroring New-NodeAttributeSet/New-EdgeAttributeSet — rankdir previously had no dedicated parameter anywhere in the module. Covers -RankDir, -Splines, -BgColor/-GradientAngle/-Style radial (gradients), -NodeSep/-RankSep, -Concentrate, -Compound, -ColorScheme, -Ratio, -Size, and graph-level font/label attributes.
• New-NodeAttributeSet: added -Peripheries, -GradientAngle, -Tooltip, -URL/-Href, -XLabel, -ColorScheme; added 'radial' to -Style and 'record'/'Mrecord' to -Shape.
• New-EdgeAttributeSet: added -Weight, -MinLen, -Tooltip, -URL/-Href, -XLabel.
• Docs updated throughout (docs/graphviz.md, Command-Graph.md, Command-Export-PSGraph.md, both existing attribute-set command pages, and a new Command-New-GraphAttributeSet.md wired into mkdocs.yml).
• CHANGELOG.md + manifest ReleaseNotes updated; ModuleVersion bumped to 3.2.0 (additive/non-breaking).

Test plan

• Full Pester suite green: 463/463 (up from the 401 baseline), including the PSScriptAnalyzer sweep and comment-based-help completeness check for the new command.
• Live-rendered every new -OutputFormat value through the real dot executable via -PassThru and confirmed non-empty output (eps, xdot, dot_json, canon, svg_inline, json0, plain-ext).
• Rendered real SVG files through both osage and patchwork.
• Confirmed -Strict actually merges a duplicate edge: two edge a b calls render as a single edge element in the rendered SVG (count verified directly).
• Rendered real PNGs for the gradient-node, colorscheme, and New-GraphAttributeSet -RankDir LR doc examples, not just checked the emitted DOT text.

🤖 Generated with Claude Code

https://claude.ai/code/session_01JkdNkQkbr85iif33Q964JX