fix(preflight): safely validate installer flags before shifting arguments

[vaibhavsrv]

Why this matters

In ods/scripts/linux-install-preflight.sh, options requiring parameter values (--json-file, --ods-root, and --min-disk-gb) immediately performed shift 2 inside the argument parser without validating parameter presence or non-empty value boundaries. When invoked with a trailing flag without an argument under set -euo pipefail, the script aborted abruptly on shift 2 with unhandled status 1 and no diagnostic output; furthermore, if another flag was passed immediately following (e.g. --json-file --strict), the subsequent flag was silently consumed as the option's value rather than being evaluated.

This fix introduces surgical option argument guards matching the established CLI validation conventions in ODS scripts. If an argument is missing, empty, or starts with a hyphen indicating another flag, the script exits immediately with status 2 and writes a clear diagnostic message to stderr (Option <flag> requires an argument). Existing valid flag parsing, output defaults, and preflight evaluation routines remain completely untouched.

Validation

• Baseline reproduction: Calling ods/scripts/linux-install-preflight.sh --json-file failed under set -euo pipefail on shift 2 with unhandled status 1 and empty stderr. Calling ods/scripts/linux-install-preflight.sh --json-file --strict silently consumed --strict as the JSON file path.
• Post-fix validation: Missing or empty option arguments or flag hijacking immediately exit with exit code 2 and display Option <flag> requires an argument on stderr.
• Telemetry: Preflight suites: 4 passed. New-test Ruff, ShellCheck, and diff checks pass; new regressions wired into Linux CI.

Overlap check

• fix: prevent loginctl interactive prompts from hanging installer #6792 focuses on loginctl session detection during environment setup; it does not touch installer preflight parameter parsing.
• fix: safely sanitize and parse .env values for opencode routing #6791 addresses string sanitization in helper routines; it does not touch option parsing in linux-install-preflight.sh.
• fix: harden python dependency installation against system-managed enviorments. #6790 hardens python dependency resolution during installation; it operates in downstream installation steps and does not overlap with preflight CLI validation.

Risk / AI disclosure

AI-assisted investigation, implementation and CLI regressions. This strengthens a CLI check, not runtime admission. Independent human review and platform/runtime qualification remain gates. No running configuration, deployment or upstream merge changed.

Follow-up integration evidence

Composed with #6795 at 28743cc without conflicts. Production and test diffs passed together; capability and preflight checks remain intact.
Backlog composition was local-only (production/test diffs, excluding workflow/Makefile wiring); it is not an upstream merge or independent human approval. Declared live-review gates remain open.

[Lightheartdevs]

Thanks for this contribution. public-beta was promoted into main on 2026-09-24 and no longer receives changes, so we're closing pull requests that target it. This isn't a judgment on the change itself. If it's still needed, please rebase onto main and open a focused PR. See #7253 for details and the contribution policy.