[FEATURE] Configurable ask breakpoints for autoCompact (200k/600k/1M-style tiers)
Preflight Checklist
- [x] I have searched existing requests and this feature hasn't been requested yet
- [x] This is a single feature request (not multiple features)
Problem Statement
Depends on / extends #<issue-1-number> (off/auto/ask mode). A single fixed "ask" prompt at one threshold doesn't map to the cost/context tiers that actually matter to a developer — a 200k checkpoint means something different from a 1M checkpoint depending on the plan and model in use, and one prompt point can't capture that.
Proposed Solution
Let ask mode offer staged breakpoints instead of a single prompt:
"autoCompact": "ask",
"autoCompactAskThresholds": [200000, 600000, 1000000]At each breakpoint the harness prompts with current usage and lets the developer choose to compact now, wait for the next breakpoint, or disable for the rest of the session.
Alternative Solutions
A single fixed "ask" prompt (as originally proposed in #63232) handles the binary case but doesn't map to cost/context tiers relevant to different plans or models — e.g. a 200k checkpoint matters differently than a 1M checkpoint depending on what the developer is paying for and how much headroom they actually have left.
Priority
Medium - Would be very helpful
Feature Category
Configuration and settings
Use Case Example
Working on a long session, I want the harness to check in at 200k ("still fine to keep going, or compact now?"), again at 600k, and again near 1M, rather than one arbitrary prompt or none at all. This turns my current manual token-watching into a structured, harness-driven decision point at each tier instead of me eyeballing the counter continuously.
Additional Context
Related: #85044 (event-based/task-boundary triggers — complementary, could combine with tiered breakpoints so a prompt only fires at a breakpoint and a clean boundary).
This is issue 2 of a 3-part split (part 1 #90137, part 3 #90139) — see also "[FEATURE] Replace autoCompact boolean with off/auto/ask modes" and "[FEATURE] Pluggable summarizer skill for autoCompact".
Note: fill in the real issue number from issue 1 in the "Depends on" line above before submitting this one.