I told my "[find a free calendar slot](https://github.com/sanand0/scripts/blob/48a095e0a956841a8e395345d31f79b1ae99d4a6/freeslots.py)" script to "[Avoid weekends and holidays](https://github.com/sanand0/scripts/commit/a8f5fb9eb5640b828618a33f2c89252e67664487#r186420170)". Wednesday vanished. Turns out it's a Singapore holiday (_**Anand**: It's [Eid al-Adha](https://en.wikipedia.org/wiki/Eid_al-Adha)_), — irrelevant for the people I was meeting in other zones. **I'd debugged my own helpful rule.** (_**Anand**: What? What does "debugged my own helpful rule" even mean?_) Annoying. But revealing. I went to ChatGPT — not to fix the script, but to think: (_**Anand**: True. I had no clue what to do._) > Could you maybe interview me to figure out what direction I might want to take this train of thought in...? Just ask me two or three questions. (The whole point was to _not_ take on more work myself.) Two questions in, it named it: **instruction debt.** (_**Anand**: which is such a cool term that I'll keep it._) > Not "bad instructions," because the original instruction was reasonable. The debt is created when a rule that once reduced cognitive load later creates invisible work, missed options, brittle behavior, or debugging cost. That hit. The script obeyed too literally. I got no warning. Worst of all, I'd scored a self-goal — given my future self an instruction that would bother me, while believing I was being helpful. --- I asked it to research further — and to mine my own agent logs as evidence. ([Local MCP](https://www.s-anand.net/blog/how-i-use-local-mcp/) runs bash; ChatGPT can read `~/.codex`, `~/.claude`, `~/.copilot` and run `~/code/scripts/agentlog.py` directly.) It came back with a taxonomy. I asked it to stress-test against more correction turns and **discard what didn't survive**. (_**Anand**: Basically, I said, analyze my logs._) It did. The robust categories, each grounded in an actual correction I'd made: - **Objective framing** — "don't base teachability on scores… base it on the pattern of errors." Wrong proxy. (_**Anand**: Oh, yeah, I was trying to find patterns of errors in student submissions._) - **Evidence/modeling** — Ticketmaster classifier overfit on `venue_name`. Predictive, not causal. (_**Anand**: True. Stupid model said, "tickets in this stadium sell more" as if it were actionable._) - **Constraint semantics** — the Singapore holiday. Hard filter where a warning would do. - **State/action** — Darwinbox: "Click Clockin" clocked me _out_. No pre/post-state check. (_**Anand**: The button said "Clock in OR out". I was clocked in. It clicked, thinking that'll clock me in, without seeing that the button was already pressed._) - **Representation/path** — blog migration: "ALL LINKS relative" broke nested URLs. (_**Anand**: Yeah, relative links in my blog have been problematic for 20 years._) - **Validation** — OCBC PDF: row balances passed, totals failed by SGD 6.9M. (_**Anand**: I'm nowhere near this rich. Codex just messed up _badly_.) ChatGPT's own self-critique was the best part: > "Lack of carefulness" should not be a category. It is not actionable. (_**Anand**: No idea what this means!) --- Then the pivot. It proposed a **60-line "Operating Contract"** for my `AGENTS.md`. I pushed back: > The operating contract is WAY too long. I was thinking 1 line, not 60... fast and frugal heuristics that cover the majority of the scenarios, rather than hard-coding everything, is what we're suggesting coding agents do in the first place. It came back with three lines. [I pasted them in verbatim](https://github.com/sanand0/scripts/commit/7be44855ac6063a364163181585b8eb5721fc469#r186421964): ``` For non-trivial tasks, define the user-visible invariant: "done means ___"; verify that invariant before claiming success. Treat constraints as soft preferences unless safety, privacy, data loss, credentials, or the current request makes them hard; surface any constraint that filters, skips, blocks, or deletes. Prefer simple, rerunnable changes: inspect real inputs/state first, use existing tools/libs, log counts/examples, and call out uncertainty. ``` Line 1 catches OCBC and clock-in. Line 2 catches the Singapore holiday. Line 3 catches the toil. **Don't add the rule to your head. Add it to the file the agent already reads.** (_**Anand**: Oh, so totally true!_)