[aliperdehan]

Roadmap 1c, second part: irspec session DIR --preview [--width N] [--height N] [--ascii] [--json].

What it does

• Prints the planned file moves exactly as --dry-run does, then, for every spectrum in DIR (loose, or already in SPA/ and jdx/), the same text irspec preview prints, headed by the title and the csv/ and plain/ names the file will get.
• Writes nothing: no folder, manifest, figure list, report, and no moved file. A loose file is read from where it lies.
• img/ pictures are listed with their planned names and a note that session digitizes them; they are not drawn.
• An existing manifest.json (peaks, titles) and --title STEM=TITLE are honoured. --preview with --dry-run means the same as --preview; plain --dry-run output is unchanged.
• --json prints exactly one object {"moves", "spectra", "images"}. Each spectrum is the irspec preview --json object plus will_be_filed_as (and title, csv, plain).
• Exit 2: DIR is not a folder, has no spectra, its manifest cannot be used, or --width/--height is too small. Exit 1: some spectrum could not be read; it is listed with its error and the others are still shown.

How

• Reuse, no copied code: organize(dry_run=True) for the moves, build_manifest (new optional planned argument: files not yet filed count as on disk and are read from where they lie; default_title gets a matching path argument), and preview.work_out_entry / render (work_out split in two; public() split out of main). No second picking or limit computation.
• tests/test_session_preview.py (19 tests): unchanged tree listing with sizes and mtimes (loose and filed folders, text, --json, --dry-run, --build/--formats), golden text for the sample .SPA, headers for the .jdx fixtures, manifest and --title honoured, pictures, --json shape, peaks and ymin equal to what a real session --build none then writes to manifest.json and figures.json, an unreadable file, QUANT-IR without peak_a, exit 2 cases, --dry-run unchanged.
• Mutation-checked: 22 mutations of session.py (writing a folder, dropping planned files, moves not printed, swapped csv/plain names, manifest ignored, exit code, absolute paths in errors, images drawn, unchecked width, extra stdout in --json, ...); all killed except one equivalent (text rendered but not printed under --json). One surviving title path got its own test, which then killed it.
• README (options table and a new section), CHANGELOG (## Unreleased) and roadmap 1c updated. __version__ not bumped, nothing tagged.

Test result

Whole suite in a throwaway venv: Ran 176 tests, OK (skipped=18). The skips are the tests that need lualatex, R, poppler or MuPDF, or the author's LR6 folders; this change does not touch those paths.

Do not merge: for the author's review.

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Generated by Claude Code