guides: address rev-code-01's review of #1313 (B1, B2, S1, S2)

All four findings reproduced before fixing. rev-code-01 was right on each.

B2 (blocker, mine). SEAT-IDENTITY provisioning step 4 said to symlink the
framework store entry to the seat slot, while the same file says those bridges
must not be recreated. The same bridge, told both ways, in one document. I
rewrote the resolution and token-location sections when the deploy made them
stale and did not carry the change into the numbered steps. Step 4 is gone and
the file now says explicitly that no provisioning step links the store to the
slot, so the omission cannot read as an oversight.

S1 (mine). The guide claimed the helper "attempts a fleet notification" on
refusal. The shipped helper does no such thing — its only reference to
notification is a comment saying an alert built on the record is best-effort, and
there is no send or wake call anywhere in the file. Now: it writes a durable
record, the record is what exists, and nobody should wait for a notification that
nothing sends. A guide that promises an alert is worse than one that promises
nothing.

S2. Estate-local content removed from files that ship to every estate: the
~/.mosaic/fleet/bin script paths (dead paths elsewhere) and the 2026-08-18 dates,
which dated a specific host's migration rather than describing behavior. The
bridge-removal passage now states the ORDERING that matters — remove bridges only
after a seat-aware helper can reach the slot, never before — which is the part
that transfers.

B1. prettier reformatted all three files. Reproduced the pipeline 2515 failure
locally before and confirmed clean after; the other three guides prettier flags
are untouched by this branch (0 changes vs origin/next) and are pre-existing.

Sanitization gate re-run and passing.

Verified for the record, since I could not verify my own work: rev-code-01
confirmed the no-fallback claim TRUE against helper content on origin/next, and
judged the evidence rules actionable on the grounds that each names an executable
replacement.

packages/mosaic/framework/guides/SEAT-IDENTITY.md

@@ -14,7 +14,7 @@ copy is drift, and drift surfaces as the stale copy returning 401 — which read
 token and sends whoever debugs it somewhere else entirely.
 
 A credential refusal is correct behavior, not a bug to route around. If git refuses with a
-fail-closed diagnostic, the fix is to provision or correct *your* identity. Escalate; do not
+fail-closed diagnostic, the fix is to provision or correct _your_ identity. Escalate; do not
 substitute.
 
 ## How a credential is resolved
@@ -22,7 +22,7 @@ substitute.
 Find the helper the way **git** does, not with `command -v`. Git runs whatever
 `credential.helper` names, and on a Mosaic host that is an absolute path — so a PATH lookup
 answers a different question and the two disagree the moment the PATH copy is removed. It was
-removed here on 2026-08-18.
+removed on hosts that have completed that migration.
 
 ```bash
 git config --get-all credential.helper     # every helper, in the order git tries them
@@ -31,8 +31,8 @@ git config --get-all credential.helper     # every helper, in the order git trie
 Git tries **each** configured helper in turn until one supplies a credential. A fail-closed
 helper supplies nothing, so a second helper configured behind it silently becomes the one that
 answers. When you care which binary serves a credential, read the whole list.
-`~/.mosaic/fleet/bin/lib-credential-helper.sh` does this correctly and handles all three forms
-git accepts (absolute path, `!command`, bare name resolved on PATH).
+Resolve all three forms git accepts — absolute path, `!command`, and a bare name looked up on
+PATH — not just the one your host happens to use.
 
 The helper resolves the identity in this order:
 
@@ -60,8 +60,10 @@ of the seat directory decides it. A seat that has a directory and an empty slot
 does not reach the service store. That is the intended behavior — the alternative is an agent
 silently acting as somebody else.
 
-If the file is unreadable the helper **fails closed**: it refuses, spools a record, and attempts
-a fleet notification. It does not fall back to a shared account. That fallback is what made
+If the file is unreadable the helper **fails closed**: it refuses and writes a durable record to
+the escalation spool. It does not fall back to a shared account. The record is what exists — any
+alerting built on top of it is a separate, best-effort concern and is not performed by the helper,
+so do not wait for a notification that nothing sends. That fallback is what made
 `usc/uconnect#3084` unattributable, and it was removed deliberately.
 
 Verify the helper you actually have:
@@ -84,8 +86,9 @@ The framework store at `~/.config/mosaic/secrets/gitea-tokens/` holds tokens for
 identities only** — identities with no seat directory. A seat's token does not belong there.
 
 Before mosaicstack#1311 the deployed helper knew only the service store, and seats were bridged
-with a symlink from the store into the slot. **Those bridges are gone** (removed 2026-08-18 by
-`~/.mosaic/fleet/bin/migrate-credentials-to-seat-slots.sh`) and must not be recreated. A symlink
+with a symlink from the store into the slot. **Those bridges must be removed once a seat-aware helper is deployed, and must not be
+recreated.** Remove them only after the helper can reach the slot without them; the reverse order
+takes every seat offline. A symlink
 is not how a system finds a credential; the helper resolving the right store is.
 
 `.principal` and `.scopes` beside the token are grant records, not secrets. They are tracked. The
@@ -97,10 +100,13 @@ is not how a system finds a credential; the helper resolving the right store is.
 2. Write `.principal` (the Gitea login) and `.scopes` (the granted scopes), mode 600.
 3. The estate operator mints the token into the seat slot, mode 600. Agents do not mint their
    own, and do not ask another agent to mint one for them.
-4. Symlink the framework store entry to the seat slot.
-5. Verify with an authenticated `GET /user` and confirm the returned login is the seat, **not the
+4. Verify with an authenticated `GET /user` and confirm the returned login is the seat, **not the
    minting account**. Record the date in `ENTITY.md`. Never record the value.
 
+There is no step that links the framework store to the slot. A seat-aware helper reads the slot
+directly; a store entry pointing at a slot is the bridge described below, and it is not part of
+provisioning.
+
 Until step 3, the seat is unminted and its git writes fail closed. That is the designed state and
 is safe to launch in — the seat is told at launch so it does not discover it mid-task.