v1.28.0 — pi-plan-build

• /pb:approach [idea]: mid-discussion, hear how Pi would approach the implementation — understanding, seams, non-goals, test strategy, alternatives, risks, assumptions, open questions (listed, never asked). Chat only: nothing is written, so /pb:spec still does the settling. With an idea it expands that one; without, it infers the one from the discussion (or compares several with a recommendation)
• Planning that pushes back: the plan, continued-plan and approach prompts share one senior-engineer stance — disagree when the idea is second-best, no objection without evidence (file:line, a constraint, or a failing test; never taste), severity labels (blocker/suggestion/nit), what would change its mind, and teaching the better idea (trade-off, principle, where the codebase already applies it). Small change, small pushback
• Plan-method fixes: baselines are per planning session (parallel planners no longer clobber baseline.json); continuing a spec in a fresh session clears the old one when it has no specs left, snapshots in the new session's tree, and tracks specs that have no progress yet; a missing snapshot warns at review time instead of silently keeping; the large-file warning lists only files changed while planning
• Follow-ups from the fresh /pb:plan review are listed in TODO.md