feat(plane): honest coverage in alerts; PHP alerts from the engine on the host

Quick mode has rules only for c/cpp, groovy, java, javascript/typescript and
python, so every PHP case's "0 alerts" read as clean. The `alerts` task now
records per language of the files read whether quick mode covers it
(derived from the bundled ruleset, not a list): coverage quick | none, with
file counts per pin, and `uncovered`. `remember` turns that into `coverage`
memory rows (a new kind; the Run passes the alerts summary.json as input),
loop-measure reports coverage per language, and improve/memory.py's M1/M2
skip a repository+pin whose coverage for the rule's language is only
`none` (counted under `coverage_none` in the proposal's excluded).

`ousast plane alerts-engine <Run.yaml> --source <frozen export>`
(plane/engine_alerts.py) does the alerts task on the host for cases whose
files include a language the engine covers but quick mode does not (PHP):
exports both pins from the case cache, runs the quick scan and the
openultrasast:dev engine container (finding_dump.py, --network none,
--memory 3g, one at a time, per-pin deadline), writes engine findings in
the alerts.jsonl row shape (rule_id engine:<family>, source engine,
in_fix_range from case.json) with a summary (files read, questions,
completed, seconds, degradations per pin), and marks the task done via
reconciler.mark_done. No result, no files read, or questions == 0 fails
loudly and leaves the run untouched. Refuses a git checkout as source.

Runner image rebuilt and re-pinned (sha256:ebb40a9a...); validation-46
regenerated (digest only). Live, recorded in
benchmarks/measurements/2026-09-30-php-engine-alerts/: froxlor 366 files,
130/130 questions per pin, 6 alerts per pin, 0 in the fix range; wp-gopay
19 files, 101/101 questions, 0 alerts. The loop: 32 run rows (coverage 8,
php=engine), 0 proposals, gate no_proposals, $0.

Co-Authored-By: Claude Opus 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01EmM1j46qgKMh3zqD1QMwEo

tests/fixtures/plane-engine/app/index.php

@@ -0,0 +1,5 @@
+<?php
+$id = $_GET["id"];
+$r = mysqli_query($conn, "SELECT * FROM users WHERE id = " . $id);
+echo $_GET["name"];
+system("ping " . $_GET["host"]);

tests/fixtures/plane-engine/probe.json

@@ -0,0 +1,29 @@
+{
+  "root": "/case",
+  "families": [
+    "injection"
+  ],
+  "seconds": 58.6,
+  "questions": 1,
+  "completed": 1,
+  "completed_regions": [
+    "app/index.php:"
+  ],
+  "degradations": [],
+  "findings": [
+    {
+      "site": "app/index.php:3:<global>",
+      "family": "injection",
+      "rung": "model_entailed",
+      "witness": "$_GET[\"id\"] -> mysqli_query($conn, \"SELECT * FROM users WHERE id = \" . $id) in app/index.php (line 3, 4 steps)",
+      "reached_from": 1
+    },
+    {
+      "site": "app/index.php:5:<global>",
+      "family": "injection",
+      "rung": "model_entailed",
+      "witness": "$_GET[\"host\"] -> system(\"ping \" . $_GET[\"host\"]) in app/index.php (line 5, 2 steps)",
+      "reached_from": 1
+    }
+  ]
+}

tests/fixtures/plane-engine/probe.stdout.txt

@@ -0,0 +1,2 @@
+read 1 files, 145 bytes; 1 regions offer ('injection',)
+{"root": "/case", "families": ["injection"], "seconds": 58.6, "questions": 1, "completed": 1, "degradations": [], "findings": 2}