[latekvo]

Closes #1338

adb emu exits 0 when the emulator console refuses a command; the only sign is a KO: line on stdout. Vega capture dropped that output. The no-PNG error now carries the reply on one line. When the reply ends in KO: unknown command (the console never authenticated adb: token missing, a symlink, or mismatched), it also names the token file adb reads. runEmuConsole (shake, fold) reports the whole reply too, so a token mismatch keeps its auth line.

The message reaches screenshot and flow snapshot: steps; settle and failed-step captures swallow capture errors by design.

Tool-server token	Before	After
mismatched	emulator console wrote no PNG to /var/…/vega-shot-q9pnX7 for emulator-5554	emulator console wrote no PNG for emulator-5554: KO: authentication token does not match ~/.emulator_console_auth_token; KO: unknown command, try 'help' (adb authenticates to the console with <HOME>/.emulator_console_auth_token, which must be a regular file, not a symlink, holding the emulator's token)
missing or symlink	same	emulator console wrote no PNG for emulator-5554: KO: unknown command, try 'help' (adb authenticates to the console with <HOME>/.emulator_console_auth_token, …)
empty reply	same	emulator console wrote no PNG for emulator-5554: empty reply

No docs update needed.

Verification

Real VVD (emulator-5554), branch dist, tool-server started with HOME pointing at a mismatched token, POST /tools/screenshot:

{"error":"[Tool:screenshot] emulator console wrote no PNG for emulator-5554: KO: authentication token does not match ~/.emulator_console_auth_token; KO: unknown command, try 'help' (adb authenticates to the console with /…/badhome/.emulator_console_auth_token, which must be a regular file, not a symlink, holding the emulator's token)","error_code":"VEGA_SCREENSHOT_FAILED","error_kind":"unknown"}

Raw adb emu screenrecord screenshot replies on that VVD (all exit 0): matching token OK\r\n + PNG; mismatched KO: authentication token does not match …\r\nKO: unknown command, try 'help'\r\n; missing or symlinked token KO: unknown command, try 'help'\r\n. captureVegaScreenshotPng and runEmuConsole from dist were run against each; the matching token still returns a PNG.

New tests in test/vega-screen.test.ts and test/emulator-console.test.ts fail on the pre-fix code; mutating the hint condition (any KO:, any line) or dropping it from runEmuConsole fails them too.

Checks: tsc --build, typecheck:tests, prettier, eslint, knip pass; tool-server vitest (6 shards) passes except flows/e2e-tool-aliases (81 vs 83 ids), which fails the same way locally on main and passes on CI.

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[latekvo]

[Diplomat, Opus 5.5]: Review of the console-reply change, findings already fixed on the branch and answered in each thread. Two PR-description claims were also corrected: coverage was narrowed to screenshot and flow snapshot: steps (settle and failed-step captures swallow capture errors), and the verification no longer shows a single-line KO reply, since real adb prints two lines on a token mismatch. Out of scope, filed as #1589: a temp dir path with a space makes the capture fail with ...: OK and leaves a stray PNG in the emulator's cwd.

[latekvo]

[Diplomat, Opus 5.5]: Second pass over the console-reply change: claims checked against AOSP adb/libbase source, sibling adb emu call sites, failure paths, telemetry export, and 13 mutants against the tool-server tests. One new finding below, plus a test gap on the existing hint-condition thread; both fixed on the branch. Out of scope, filed as #1698: the preview window's "Shut down" reports success when the console refuses adb emu kill.

[latekvo]

Folded into #1753 as 9e88b93, to review together with the other capture fixes.