Rewrite the README sentences that fail the prose rules or disagree with the code

A fresh read of README.md whole against the rules of issue 157, with every
statement except measured figures checked against the code on next. Four
sentences fail the prose rules, all in sections added since 742e759: the
origin change definition, the first uses of TTL and SOA record, and the
geojs request. Five disagree with the code: the geojs request carries only
the addresses the cache does not hold; after a write fails on SQLite's hard
heap limit, the prefix handler also writes its origin changes again, and
the PTR and geolocation caches write their answers again; the test rerun on
failure drops -cover; and latitude and longitude are in degrees, which
their names do not say.

Model: fable-5-1

README.md

@@ -197,8 +197,9 @@ also carries an `@meta` object:
 - `api_version`: `1`
 - `execution_time_ms`: the number of milliseconds the request took
 
-Every value with a unit is a number, and the unit ends the field name. Examples
-are `_ms`, `_seconds`, `_bytes`, `_per_sec` and `_per_min`.
+Every value with a unit is a number. The unit ends the field name, as in `_ms`,
+`_seconds`, `_bytes`, `_per_sec` and `_per_min`. `latitude` and `longitude` are
+in degrees, and their names do not say so.
 
 The paths:
 
@@ -705,8 +706,10 @@ What happens at each limit:
   allocating more.
 - The SQLite hard heap limit: a database statement fails with an out-of-memory
   error, which the handler logs. The prefix handler writes the routing table's
-  changes and its origin changes again in a later write. Everything else in the
-  failed write is dropped. The process keeps running.
+  changes and its origin changes again in a later write. Everything else in a
+  handler's failed write is dropped. The PTR cache and the geolocation part
+  write their answers to `cache.db` again in a later write. The process keeps
+  running.
 - The handler queues: the handlers are the four parts that take the feed's
   messages (see Design). The prefix handler's queue holds at most 100,000
   messages, about 100 MiB. Each of the other three holds at most 20,000. When a

TODO.md

@@ -30,7 +30,7 @@ run of `742e759`, which has every fix but one, dropped no update except after
 the feed stalled. That cause, https://git.eeqj.de/sneak/routewatch/issues/229,
 is fixed on `next`.
 
-A 24-hour run of `e58c663` on the live feed began at 09:19 UTC on 2026-11-10
+A run of `e58c663` on the live feed began at 09:19 UTC on 2026-11-10
 (https://git.eeqj.de/sneak/routewatch/issues/232). It is to confirm that fix.
 Next Step lists what its outcome reports. The seven IP lookup additions of
 https://git.eeqj.de/sneak/routewatch/issues/203 landed after it began, so it
@@ -41,7 +41,7 @@ https://git.eeqj.de/sneak/routewatch/issues/86.
 
 # Next Step
 
-Post the outcome of the 24-hour run of `e58c663` on
+Post the outcome of the run of `e58c663` on
 https://git.eeqj.de/sneak/routewatch/issues/232. The run lasts at least 24
 hours. If the feed has not stalled or reconnected by then, the run goes on until
 it does, up to 72 hours in all. The outcome says:
@@ -59,11 +59,12 @@ File an issue for each problem the run finds.
 
 - 2026-11-10: `README.md` and this file are read whole against the rules of
   https://git.eeqj.de/sneak/routewatch/issues/157, and every statement except
-  measured figures is checked against the code on `next`. Six README sentences
-  are rewritten. Four failed the prose rules, on origin changes, PTR lookups and
-  geolocation. Two disagreed with the code, on a failed database write and
-  `script/test`. Status and Next Step describe the live-feed run in progress
-  (closes https://git.eeqj.de/sneak/routewatch/issues/251).
+  measured figures is checked against the code on `next`. Four README sentences
+  failed the prose rules, on origin changes, PTR lookups and geolocation, and
+  five disagreed with the code, on units, geolocation, a failed database write
+  and `script/test`. Each is rewritten. Status and Next Step describe the
+  live-feed run in progress (closes
+  https://git.eeqj.de/sneak/routewatch/issues/251).
 - 2026-11-10: the image creates the `routewatch` user as a regular user with UID
   1000, so the build no longer warns about the system UID range (closes
   https://git.eeqj.de/sneak/routewatch/issues/248).