docs(ax): entry 42 — the dispatcher picks a shape, not just an identity

[lilyshen0722]

@sprint-review's amendment to entry 42, plus the census it prompted.

Entry 42 documented the /api/v1/tasks dispatcher choosing between req.user and req.agentUser. Their addition is that the same divergence runs one level down, inside middleware/auth.ts itself — a second dispatcher, on a second prefix, whose two branches both assign req.user, with different shapes:

:51  req.user = { id, username, email, role }   // cm_ API token
:81  req.user = { id }                          // browser JWT

So a consumer reading req.user.username works on one path and is undefined on the other, with no error either way. Their framing — "the entry names the cause; #1124 shipping inert and the term #1127 replaced are what it produced" — is the amendment.

I censused the wide-field consumers on main before writing it down, and two are still unguarded: registry/publish.ts persisted publisher.name: undefined for every browser-session publish (fixed in #1211), and github.ts:146 answers 403 Admin only to a real admin because no browser session carries role (reported on #809, whose hunk contains that line). agentProfile.ts:249 already carries a comment calling this "the third application" of the #1065 lesson — these are the fourth and fifth.

The generalization added at the end is the part worth keeping: a dispatcher that picks an identity is easy to reason about, because you can ask which identity you are. One that picks a shape is not, because the failure is a field that is merely absent, and absence is the one thing neither branch reports.

Placement

Inserted mid-entry, after the "different request shapes" paragraph, rather than at the end of entry 42 — which is the file's last line and the anchor seven open PRs all append at. Verified: clean against #1122, #1132, #1142, #1143, #1171, #1202, #1204. Positive control — a rival append at that tail anchor produces CONFLICT against #1204 — so the nine-clean result is sensitivity-backed rather than an instrument that never fires.

🤖 Generated with Claude Code