Single-line file selection doesn't expand to enclosing symbol (off-by-one)

Description

Referencing a file with a single-line selection (startLine === endLine) should expand the read range to the enclosing symbol via documentSymbol. The check in packages/opencode/src/session/prompt.ts compares
.start.line (LSP 0-based) against start (1-based selection), so it never matches. The agent reads only the single selected line instead of the whole symbol.

Plugins

None

OpenCode version

dev

Steps to reproduce

1. Attach a file with a single-line selection placed on a function/class definition.
2. The agent reads only that one line instead of the enclosing symbol.

Operating System

Windows 11

Terminal

Windows Terminal