Record the first instrumented coverage measurement, and classify the 32 it found

E8. The instrumented suite had never been measured: enableAndroidTestCoverage was
unset, so a connected run emitted no .ec at all, and jacocoTestReport reads only
testDebugUnitTest. Measured on API 34 by setting the flag temporarily.

  JVM     2236/2374 line 94.2%   1171/1338 branch 87.5%
  E2E     1711/2374 line 72.1%    669/1354 branch 49.4%
  UNION   2342/2374 line 98.7%   1212/1354 branch 89.5%

The JVM row reproduced the committed figure exactly, which is the control that
says both exec sets match the current class files.

The device suite closes 106 lines the JVM suite misses, and the first four are
the 81 wave 4 wrote off as native or device edges -- FFmpegEngine 32,
Media3Engine 24, ConcatEngine 15, MainActivity 10. The union leaves one. That
confirms the read's own hypothesis rather than overturning it; nobody had
measured past the boundary it named.

All 32 lines reached by neither suite were read, and none is an e2e test gap:
nine are compiler-generated, ten are getForegroundInfo() for expedited work this
app never enqueues (#252), three are F5, three are uncalled members (#253), one
is the Vorbis encode arm (#254), and four are F4-shaped error guards.

MediaProbe:210-212 gained a measurement rather than an assumption. F7 ruled
probeWithExtractor's catch unreachable because Robolectric's MediaExtractor never
throws; probeWithFFprobe calls native ffmpeg-kit, so that reasoning does not
transfer. But probe() calls both, and RemuxTest drives it with garbage bytes on a
device -- so the ffprobe path has had malformed input on real hardware and did
not throw. Same conclusion as F7, different mechanism, now on record.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

docs/e2e-read-findings.md

@@ -437,3 +437,81 @@ green on `main`.
 the same wave, and the tests it writes are no more self-describing than the ones it audited. The
 check that found it is the one this document already recommends: **read the KDoc against the code,
 not against the ticket.**
+
+## E8 — the instrumented suite's coverage, measured for the first time
+
+**Severity: n/a · Measured 2026-09-06 on API 34 · the number had never existed**
+
+Four coverage waves were steered by a figure that cannot see `app/src/androidTest`. Nothing had
+ever produced the other half, because `enableAndroidTestCoverage` was unset, so a connected run
+emitted no `.ec` at all and `jacocoTestReport`'s execution data names only `testDebugUnitTest`.
+
+Measured by setting that flag temporarily, running `run-e2e.sh 34` (70/70, 0 failed, 3m21s — the
+instrumentation destabilised nothing), and reporting the resulting `.ec` against the **same** class
+directories and exclusions the committed task uses:
+
+| suite | line | branch |
+|---|---|---|
+| JVM `testDebugUnitTest` | 2236/2374 — **94.2%** | 1171/1338 — **87.5%** |
+| Instrumented, 70 tests | 1711/2374 — **72.1%** | 669/1354 — **49.4%** |
+| **Union** | 2342/2374 — **98.7%** | 1212/1354 — **89.5%** |
+
+The JVM row reproduced the committed figure exactly, which is the control: both exec sets match the
+current class files, so the union is trustworthy.
+
+**Two caveats before anyone quotes these.** Branch denominators differ by 16 — 1338 against 1354 —
+entirely inside `MediaProbe`, an artefact of offline versus on-the-fly instrumentation; line
+denominators are identical at 2374, so only the line figures compare exactly. And **72.1% is not a
+grade for the instrumented suite.** Seventy end-to-end tests reach code broadly and choose arms
+rarely; a branch figure of 49.4% is what that shape looks like. This whole document exists because
+the gaps that mattered — #223's vacuous assertions, #238's two covered things nobody combined —
+are invisible to any percentage.
+
+### What the device suite is for, in numbers
+
+It closes **106 lines** the JVM suite misses, and they are precisely the ones wave 4 wrote off:
+
+| file | JVM missed | union missed |
+|---|---|---|
+| `FFmpegEngine.kt` | 32 | **0** |
+| `Media3Engine.kt` | 24 | **0** |
+| `ConcatEngine.kt` | 15 | **0** |
+| `MediaProbe.kt` | 13 | **3** |
+| `MainActivity.kt` | 10 | **1** |
+| `AndroidDeviceCodecs.kt` | 8 | **0** |
+| `Transcoders.kt` | 10 | 3 |
+
+CLAUDE.md's wave-4 read called 81 lines "native or device edges" — `FFmpegEngine` 33,
+`Media3Engine` 24, `ConcatEngine` 14, `MainActivity.onCreate` 10. The first four rows above total
+**81**, and the union leaves **1**. That **confirms** the read's own hypothesis rather than
+overturning it: it always said those zeroes were "the `testDebugUnitTest`-only measurement
+boundary". Nobody had measured past the boundary. `AndroidDeviceCodecs` is the pointed one — #194
+was filed to cut a seam because `probe()` could not be reached, and on a device it is fully covered.
+
+### The 32 lines neither suite reaches, classified
+
+Every one was read. **None of them is an e2e test gap**, which is the result:
+
+| lines | where | classification |
+|---|---|---|
+| 9 | `Transcoders` ×3, `ConversionViewModel`, `ConverterScreen`, `JoinViewModel`, `JoinScreen`, `MainActivity`, `Reattachment` | **compiler-generated** — default-arg `$default` bridges, coroutine completion, the synthetic `NoWhenBranchMatchedException` arm of a `when` over `Destination` |
+| 10 | `ConversionWorker:342-346`, `ConcatWorker:132-136` | `getForegroundInfo()` — WorkManager's **expedited-work** hook, and nothing here enqueues expedited work. The live path is `setForeground(foregroundInfo(...))`, which is covered. **#252** |
+| 3 | `ConversionNotifications:60-62` | **F5** — `areEnabled()` has no callers. Already on record |
+| 3 | `CopyPlanner:28`, `OutputFormat:222-223` | public members with no callers. **#253**, with F5 |
+| 3 | `MediaProbe:210-212` | `probeWithFFprobe`'s `catch` — **F7's sibling, and now measured**. See below |
+| 2 | `FFmpegCommandBuilder:167-168` | `COPY`/`NONE -> error(...)` — F4-shaped, deliberately exempt |
+| 1 | `FFmpegCommandBuilder:188` | the `VORBIS` encode arm. No `OutputFormat` produces it, but `ContainerCapabilities` lists it for WEBM and OGG. **#254** |
+| 1 | `ConversionWorker:231` | `?: error("Could not open the input file.")`. `UnopenableUriTest` fails the job *downstream* of it, so the elvis is unprovoked — F4-shaped, same as the two above |
+
+**`MediaProbe:210-212` is the one that gained a measurement.** F7 ruled `probeWithExtractor`'s catch
+unreachable because Robolectric's `MediaExtractor` never throws. That reasoning does not transfer:
+`probeWithFFprobe` calls `readMediaInformation` in native ffmpeg-kit, which the JVM never loads.
+But `MediaProbe.probe` calls **both** probes on one line, and
+`RemuxTest.probeDistinguishesAudioFromImagesFromRubbish` drives it on a device with 4096 bytes of
+garbage — so the ffprobe path *has* been given malformed input on real hardware and **did not
+throw**. Same conclusion as F7, reached by a different mechanism, and now on record rather than
+assumed.
+
+**The reusable part**: a union report is what separates "no test calls this" from "only a device
+calls it", and neither report alone can. Six of the eight rows above were indistinguishable from
+real gaps in the JVM-only number.