Inspect expression and control flow

Choose the analysis for the question left unanswered by reading source.

Question	Tool and boundary
Which variables enter, leave, change or become captured?	analyze-data-flow: exact expression, complete statement or contiguous sibling statements.
Can this region complete, exit or return?	analyze-control-flow: complete statement or contiguous sibling statements within one executable body.
How does the compiler interpret an expression?	get-operation-tree: Roslyn IOperation kinds, types, constants and locations.
How do branches connect across a body?	get-control-flow-graph: selected executable symbol or the body enclosing a location.

Select an exact region

Region-flow analysis requires exact syntax spans. A caret, partial statement or approximate selection is unsuitable; leading/trailing trivia outside the syntax span can cause rejection. Reuse a verified span or construct one from the actual source using selectors.md.

For extraction, inspect the proposed region with get-code-context. Use data flow when parameters, outputs or closure behavior need clarification; combine reads/writes, declarations, captures and flow-in/flow-out rather than inferring the signature from one category. Use control flow to examine statement-range exits and returns. Each category is independently bounded, so check the relevant collection before concluding a variable or exit is absent. Continue through code-actions.md for a supported extraction.

Check what was projected

get-operation-tree may fall back from the selected syntax node to the first immediate child with an operation. Check the returned root's kind and location. Result/node truncated flags identify omitted structure.

get-control-flow-graph returns the enclosing executable body's graph, not a graph clipped to the selected text. Successor ordinals can point to blocks omitted by the cap. Inspect outer and nested truncation before concluding an edge or branch is absent.