---
name: dont-infer-a-mechanism-from-wording-open-the-emitter
description: "Reading a breadcrumb's or an assert's WORDING as a product behaviour invents mechanisms; open the emitter — a decline's sibling branches and a rig's assert string are the two faces that cost me an afternoon."
metadata:
  type: feedback
---

Twice in one afternoon (2026-09-08, v0.68.0 golden r1 triage), I reasoned from a
STRING to a MECHANISM without opening the code that emits it, and both times a peer
had to correct it:

1. **A breadcrumb's wording.** `HELPER_SERVE_FOR: … reason=the delivered body is not
   an envelope` looked like same-seam evidence for the sha's known envelope defect. It
   is not: at `wan.rs` `request_quoted_paths` that text is the `parse_event` →ic `None`
   branch (a body that arrived RAW), and the sibling branch — the one a malformed
   envelope would hit — carries DIFFERENT text (`envelope type is …, not a user-msg`).
   A doubled attribute parses fine. **The sibling branches are the discriminator**, and
   they are invisible unless you open the emitter.
2. **A rig's assert string.** `"A answered NoReply — dialled, but took no custody"`
   reads as the peer having refused. `NoReply` is minted at exactly ONE site, the
   stream-EOF arm of the requester's own read loop — it is never a token a peer sends.
   Nothing refused; the stream was accepted and never read. I had built a whole
   "admission/custody defect plus a missing breadcrumb" finding on a TEST's phrasing.

**One rule, not two: a message string tells you which branch of the EMITTER ran, and
nothing about who caused it.** Before a wording becomes a mechanism in anything you
send: open the emitter, read its sibling branches, and check whether the string is
even the product's (a rig's assert wording is the test author's sentence, not the
system's report). One `sed -n` over the file would have caught both.

Corroborating timing check that settled #2 independently: a refusal answers in
milliseconds; this returned 1,248 s later, five minutes after the peer's process
exited — i.e. an idle-timeout EOF. **A latency shape is evidence about a mechanism
class** and is cheap to look at.

Kin: [[parent-chain-attribution-must-walk-to-a-root]],
[[a-watchers-exit-0-with-an-absent-exit-file-is-a-non-result]] — the same family: a
narrow instrument (one parent level, a wrapper's exit, a string) reported as if it
measured the wide thing.