釜底抽薪 — remove firewood from under the cauldron

釜底抽薪 (fǔ dǐ chōu xīn) — "remove the firewood from under the cauldron". Stop the boiling by removing the fuel, not by lifting the lid. Strike at the obvious causal root, not the symptom.

This is the default debugging frame for the chengyu-skills set. When causal tracing fails or the root is genuinely not causal, escalate to chengyu-besiege-wei-save-zhao (indirect / political redirect).

When the user is about to patch a symptom

Symptoms that this schema applies:

• "Add a retry" — usually means "I don't know why it fails; please paper over it." The fuel is whatever is causing the failure.
• "Increase the timeout" — the fuel is whatever is making the operation slow.
• "Catch and ignore the exception" — the fuel is whatever is throwing.
• "Add if x is None: return" without understanding why x is None — the fuel is whatever is setting None upstream.
• A bug keeps "coming back" in different forms — the fuel is a structural issue, not the specific bug.
• A test is flaky — the fuel is whatever the test depends on that's non-deterministic.

Behavior

1. Ask what produces the symptom. Trace upstream until you find something that, if removed or changed, makes the symptom impossible — not just unlikely.
2. Distinguish defensive code from cause-fixing code. A try/except at a system boundary is fine. A try/except around your own code that hides a bug is firewood-feeding.
3. Name the root cause explicitly. "The retry is hiding the fact that we hold the DB lock too long" — tell the user what the firewood is, even if you ultimately decide to leave it.
4. Decide consciously to symptom-patch. Sometimes the root fix is too expensive right now. That's fine — but say it explicitly: "Symptom patch for now, root cause is X, ticket Y."

When 釜底抽薪 is exhausted, prompt for 圍魏救趙

If you have traced upstream and cannot find a causal root that you can act on (the cause is in someone else's codebase, in human politics, in a maintainer's priorities, in CI bureaucracy) — explicitly tell the operator:

"I've exhausted the causal frame here. The root is [X], but I can't act on [X] directly. Consider chengyu-besiege-wei-save-zhao — is there an indirect move (related issue, benchmark, adjacent argument, reframe) that would force [X] to move?"

The operator then decides whether to authorise the indirect move. Don't try to do 圍魏救趙 unilaterally — that requires operator-side political knowledge you don't have.

Anti-pattern

Calling root-cause analysis until the heat death of the codebase. Some symptoms genuinely are leaf-level (a typo, an off-by-one). The test for 釜底抽薪 is: does the same class of symptom show up elsewhere, or will fixing only here let it resurface tomorrow? If symptom is isolated, fix the symptom and move on.

Etymology

From a Han dynasty military text. To stop an army, don't fight it head-on — cut its supply lines, take its grain, and it collapses on its own. The cauldron boils because of the firewood; remove the firewood and the boiling stops without ever touching the cauldron.