Native read-only /view: files, logs, output and document previews #397

Goal

Design a lightweight read-only NMSh-native /view surface for files, logs, Markdown, diffs and previously completed command output. The user likes the GUI-like discoverability of TTT Editor, but does not want NMSh to become a second full text editor or terminal emulator.

This is post-v0.20 exploratory scope, not release work or authorization to implement. Audit the existing Actions → Open in pager (less), /open host actions, bat/delta Theme Bridge, transcript folding, search, Compare, and the pending shared /copy//actions navigator before designing anything.

Proposed user experience (commands are proposals, not shipped)

• /view path/to/file → read-only document viewer; /view may offer a reviewed file/output selector.
• From a completed command block, Actions → View full output reuses the same backing output, with no duplicate capture or secret disclosure.
• Search/find, line numbers, go-to-line, optional syntax highlighting, horizontal scroll/wrap, copy selected text or full output, and stable viewport/selection across resize.
• Useful optional Markdown rendering and diff/log presentation; raw text must stay accessible. No implicit reinterpretation of script/machine-readable output.
• Familiar concise status/help, background-focused selection, mouse + keyboard parity, Safe/NO_COLOR, narrow widths. Borrow interaction principles from TTT and Ranma without copying their UI wholesale.
• Prefer reuse of existing transcript renderer, search, selection, FoldPolicy and HistoryViewport/future scrolling infrastructure. Don't introduce a second authoritative output store or alternate PTY manager.
• For very large/binary/remote files, provide honest bounded behavior and a documented fallback to existing less, bat, Glow or host editor; optional tools are never prerequisites.

Explicit boundaries

• No native editing, file writes, undo/redo stack, LSP, multi-cursor, integrated IDE, or independent terminal emulator. Editors like TTT/Fresh/Micro/Helix/Neovim/Zed remain external and independently owned (Workflow integrations: external editors, search, preview tools and shell utilities #366).
• Viewing must not execute/shell-source inspected content, invoke a tool with unreviewed command-line text, rewrite terminal-host config, or steal keystrokes from a foreground read/alternate-screen program.
• Preserve source bytes/encoding where supported, explain encoding/binary/truncation limitations, protect large-file latency and memory on an 8 GB Mac.
• Raw PTY output in NMSh history remains authoritative; /view and semantic views are presentation-only, no changes to pipes, redirections, /copy, exports, or command exit codes.
• No default upload or network transmission of file content.

Acceptance / design gate

• Inventory existing pager, host-open, transcript navigation, copy/actions and theme integration; identify concrete gap against external less/bat/TTT before implementing.
• Show a production-renderer preview/flow for a source file, Markdown file, 400-line stored output and 10k-line log, at 32/80/120 columns.
• Specify file read limits, Unicode/control escaping, follow/tail policy, sensitive content treatment and keyboard ownership.
• Read-only file/path/line handling, missing/unreadable files, symlinks, binaries, search/copy and pagination tested without user-file mutations.
• Real macOS Ghostty/Terminal.app QA, Linux portability, resize/selection/passthrough, CPU/memory measurements.
• If the gap is small, prefer improving existing Open in pager over shipping redundant /view UI.

Related

#366 optional editor/viewer integrations; #386 semantic output (different: derived interpretation of completed output); #335 contextual keybindings; #304 Theme Bridge; #14 PTY/TUI compatibility; #330 terminal-first workspace boundary.

References: TTT Editor, Ranma, bat, Glow.