Close eight open SDK tasks: the pidfile, the log, cards, names and a live curve

Each was a loose end recorded under `### SDK` in the notepad.

`serve` takes its own pidfile down on SIGTERM. uvicorn restores the handler it
found and re-raises the signal it stopped on, so the default handler ended the
process without unwinding and the `finally` never ran — which is what a stop
sends, and what left `serve.pid` behind.

`serve.log` is cut back past 5 MB by the engine rather than by the screen that
started it, so an adopted engine is bounded too. Gated on its own stdout being
an appended regular file, which is what makes the cut safe: the kernel then
puts the next write at the new end.

Cards are counted from `/dev/nvidia[0-9]*`, so `FLOW_GPUS`/`--gpus` of 0 means
"work it out" the way `FLOW_CPUS` always has. The engine counts, not the
accountant — a remote worker builds one of those from its own inventory, and
detecting there would hand it the engine host's cards. The worker counts last:
what a batch job says it was granted still wins.

`GET /runs/metrics/names` is the distinct over a selection that `--list` and
the terminal's metric picker were approximating by reading the newest run that
had measured anything, which missed a name only an older run ever wrote.

`MetricSink` announces each batch it has written (`run_metric`, carrying the
names). Not a per-point event: one covers up to 500 points or two seconds of
them, and the rows stay the record. The terminal comparison fills in as the
first readings land instead of staying blank until reopened, and the browser
refetches the run and any comparison rather than the list behind them.

`retry --group` pages the list route by `before` instead of stopping at 500.

The terminal dashboard takes the terminal's colours (`ansi-dark`), and the web
UI can re-pair from Settings without disconnecting first.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PRQ9bmTvCbqCwXo9mxZzzV

docs/code/cli.md

@@ -77,12 +77,14 @@ Another instance's Fluksio on the port is named, and the move happens as usual.
 | `--max-runs N` | 4 | batch runs driven at once (`FLOW_MAX_RUNS`) |
 | `--max-cascades N` | 4 | cascades in flight at once (`FLOW_MAX_CASCADES`) |
 | `--max-workers N` | 4 | python worker processes (`FLOW_MAX_WORKERS`) |
-| `--gpus N` | 0 | GPUs on this machine a node may be given (`FLOW_GPUS`) |
+| `--gpus N` | counted | GPUs on this machine a node may be given (`FLOW_GPUS`) |
 
-Cards are declared rather than detected, since asking a vendor's tooling would
-make one dependency two, so a machine with a GPU reports none until `--gpus` says
-otherwise, and a node asking for one is clamped to zero and runs alongside
-every other. `--gpus 1` is what serialises them.
+Cards are counted from NVIDIA's device nodes (`/dev/nvidia0`, `/dev/nvidia1`, …),
+which asks no vendor tool and so keeps the one dependency from becoming two.
+Anything they do not cover — another vendor, or a card this process cannot see
+— reports none until `--gpus` says otherwise, and a node asking for one is then
+clamped to zero and runs alongside every other. `--gpus 1` is what serialises
+them. Passing a number always wins over the count.
 
 `--enroll` with `--portal` is the one-command setup: it pairs before the engine
 starts, so the connection is dialled as part of coming up rather than needing a
@@ -147,6 +149,11 @@ which is what lets the screen be closed while the engine keeps running — a
 pipe with nobody reading it breaks the next line the engine writes, and a
 node's `print` is one of those. It also means the Logs tab has the output of
 an engine this screen only adopted, and the scrollback of the one before it.
+The engine cuts the file back to nothing once it passes 5 MB, so the bound
+holds whether or not a screen is open.
+
+The screen takes its colours from the terminal rather than painting its own,
+so it sits inside a light profile as readily as a dark one.
 
 An engine started elsewhere is adopted rather than duplicated, and can be
 stopped from here only when it is this instance's own: both the pidfile
@@ -502,7 +509,8 @@ taken leaf by leaf rather than as one blob.
 
 Metric names are flow-qualified (a node of `train` writing `train_loss` records
 `train.train_loss`) so `--list` prints the names the selected runs
-carry when the spelling is not obvious.
+carry when the spelling is not obvious. The engine answers it over the whole
+selection, so a name only an older run ever recorded is listed too.
 
 Both take `--flow`, `--run ID` (repeat it), `--group`, `--status`, `--since`,
 `--until` and `--local`, and both put the run id on every row: it is the join