10. One dual-mode binary: scriptable CLI and interactive TUI

Context

The suite serves two working styles from the same evidence. A pipeline needs a scriptable, machine-readable CLI; an analyst exploring session state interactively wants a terminal viewer. Shipping two binaries would fork the distribution and the parser wiring; folding the interactive render loop into the CLI library would make the CLI hard to test and couple it to a TUI toolkit.

Decision

Ship one binary, br4n6, that runs in two modes. With a subcommand it runs a scriptable handler that emits text / jsonl / csv; with no subcommand, or br4n6 tui, it launches an interactive vi-keyed terminal viewer for session state. The CLI library stays decoupled from the render loop: run takes an injected launch_tui callback (a Humble Object seam), so the argument parsing and every scriptable handler are unit-testable while the irreducible interactive loop lives in the binary's main.

Consequences

One distribution covers both working styles, over one set of parsers. The scriptable surface is fully testable; only the thin interactive shell is not. The injected-callback seam keeps the TUI toolkit dependency out of the library's test matrix.

Status

Accepted.