feat: capture opt-in instruction context

[caioribeiroclw-pixel]

Summary

• add an opt-in --instruction-context snapshot flag that hashes known local instruction files without recording raw prompt/transcript/instruction text
• parse and expose instruction_context in snapshot history/details JSON
• cover the shell helper behavior with a regression test

Why

This is the small v1 shape discussed in #323: snapshot-local causality metadata so a later audit can tell whether a bad edit likely came from a changed instruction/rule surface rather than only the target file diff.

Validation

• git diff --check
• npx tsc --noEmit
• npx biome check bundled-skills/pony-trail/scripts/snapshot_change.sh src/runtimes/ponytrail/snapshots.ts src/cli.ts tests/pony-trail-script.test.ts
• sh -n bundled-skills/pony-trail/scripts/snapshot_change.sh
• manual shell smoke for --instruction-context verifying AGENTS.md is hashed, CLAUDE.md is marked missing, and raw instruction text is not present in instruction_context

Note: I could not run bun test locally because this container does not have bun installed; the Husky pre-commit hook failed for the same reason, so the commit was made after the checks above.

[0xroylee]

Thanks for the PR. CI is green now, and the feature direction is useful. I think there are still two issues worth fixing before merge: one safety boundary around symlinked instruction files, and one usability gap in the human history --details output.

[0xroylee]

[blocking] This hashes $root/$rel_path without resolving the target and checking that it still lives inside $root. Because .cursor/rules/* can include symlinks, --instruction-context can hash a file outside the workspace while reporting only the workspace-relative symlink path. I reproduced this with .cursor/rules/external.mdc -> /private/tmp/...; the snapshot marked it captured and logged the external target hash. Please skip symlinks/out-of-root resolved paths, or mark them with a non-captured warning status.

[0xroylee]

This makes the details view less useful than the issue asks for. history --json includes the file paths and hashes, but history --details only prints a count and raw_text=false, so a human cannot compare which instruction file changed between snapshots. Please render at least path, status, bytes, and hash prefix/full hash in details mode while keeping the default compact view small.

[caioribeiroclw-pixel]

Thanks for the detailed review. I saw #325 landed the project-owned implementation path, including the instruction-context CI fix, so I’m going to close this PR rather than keep a conflicting fork branch alive.

The two review points still look important for the merged implementation too:

• symlinked instruction files should probably be marked as skipped_symlink / outside_workspace rather than followed silently
• history --details should expose the compact instruction-context summary so users don’t need to inspect JSON to notice changed instruction hashes

Happy to test or review a follow-up if useful.