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@@ -36,6 +36,56 @@ approach:
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repo), so it stays runnable without a printer and without network access to a
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real device.
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## Investigation result (tasks 1.1–1.3)
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Measured on `printserver:latest` (`cups-daemon 2.4.2-3+deb12u9`, `cupsfilter`/
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`gs` present in the image), container started with
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`PRINTER_OPTIONS="BRColorMode=None TonerSaveMode=True"`.
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**The `TonerSaveMode` queue default does reach the job.** The emitted PostScript
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carries the option branch for the queue default; the vendor `False` default only
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appears when the option is not set at all:
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| options supplied to the filter | `%%BeginFeature` emitted | effect line |
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|---|---|---|
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| none (bare PPD, vendor defaults) | `*TonerSaveMode True` | `…begin true tonersave end…` |
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| `BRColorMode=None TonerSaveMode=True` (queue defaults) | `*TonerSaveMode True` | `…begin true tonersave end…` |
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| `BRColorMode=Vivid TonerSaveMode=False` (job's own) | `*TonerSaveMode False` | `…begin false tonersave end…` |
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| `BRColorMode=None…Vivid` variants | `*BRColorMode None` / `*BRColorMode Vivid` | `<</UseCIEColor false>>` / `true` |
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An explicit per-job option visibly wins in the same channel (row 3, and
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`None`→`Vivid`), so the job-level path is real and settable — not a fixed
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vendor value.
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**The `*False` in `lpoptions -p <queue> -l` is a display artefact, not a lost
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setting.** All three views of the same container agree that the setting *is*
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stored — `/etc/cups/ppd/<queue>.ppd` line 328 `*DefaultTonerSaveMode: True`,
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cupsd's live
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`GET /printers/<queue>.ppd` (the same PPD cupsd uses for filtering) also
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`*DefaultTonerSaveMode: True` — while `lpoptions -p <queue> -l` renders
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`TonerSaveMode/Toner Save: *False True`, stable across three separate
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containers. Cause: `TonerSaveMode` is a PPD **Boolean** (`*OpenUI
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*TonerSaveMode … : Boolean`), and for a Boolean `lpoptions -l` marks the
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*False/Off* entry as current instead of reflecting the keyword default; the
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`PickOne` option `BRColorMode` reflects `*None` correctly. The ordering is a
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rendering rule, not a second copy of the setting — so the misreading that opened
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this change is an *observation* defect (the wrong view was trusted), and
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`lpoptions -l` must not be used to assert a `TonerSaveMode` default.
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**Method caveat found during the probe (affects D2).** A job submitted with the
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usual `lp -d <queue>` never reached the spool file in a usable state here: the
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client's `d0000N-001` still holds the **original PDF** (cupsd retains it until
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the printer accepts the job), and the job sticks at "The printer may not exist
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or is unavailable", so no filters run and no PostScript exists to inspect.
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`cupsfilter -j <job-id>` cannot read cupsd's job without the control file
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(`c0000N`) inside the container, which is not worth reconstructing. The working
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reproducible route is therefore **`cupsfilter -p <queue-ppd> -m
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application/vnd.cups-postscript -o <opt=value> <sample>`**, with the queue's PPD
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copy from `/etc/cups/ppd/<queue>.ppd` — it emits the same
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`%%BeginFeature`/effect-line structure the queue path produces and needs no
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printer. This implementation uses that route; the "read cupsd's own spool" idea
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in D2 is recorded there as unworkable in this environment.
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## Goals / Non-Goals
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**Goals:**
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@@ -69,19 +119,25 @@ Alternatives considered: `printers.conf` `Default*` lines (absent with this
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CUPS — rejected); the CUPS web admin page (same settings source, needs auth —
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rejected); `lpstat -l -p` (no option detail — rejected).
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**D2 — Acceptance signal is the emitted PostScript spooled by cupsd.**
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Rationale: it is the only artefact that shows what the printer receives, it
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covers presets, queue defaults and per-job options in one channel, and the
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existing spec already reasons in those terms (`<</UseCIEColor false>>`). The
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spool file is the last file in `/var/spool/cups/d<JobId>-*` (its name comes from
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the preceding `lpstat -W completed -o` line), and is readable as root inside the
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container for a few minutes while the socket connection to the placeholder
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`PRINTER_IP` fails.
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**D2 — Acceptance signal is the emitted PostScript, produced by `cupsfilter`
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with the queue's PPD.**
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Rationale: the emitted PostScript is the only artefact that shows what the
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printer receives, it covers presets, queue defaults and per-job options in one
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channel, and the existing spec already reasons in those terms
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(`<</UseCIEColor false>>`). The concrete command is
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`cupsfilter -p /etc/cups/ppd/<queue>.ppd -m application/vnd.cups-postscript -o
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<opt=value> <sample>`, run inside the container, asserting on `%%BeginFeature:
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*<Name> <Value>` lines and the effect line that follows. "Read cupsd's own spool
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file after `lp`" (the original form of this decision) was **disproved by the
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investigation**: without a reachable printer the filters never run, so the spool
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holds the unfiltered input, and `cupsfilter -j` needs a control file cupsd does
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not write in this state. Set-six is captured where later reasoning needed it.
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Alternatives considered: asserting on `lpoptions -l` alone (that is exactly the
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blind spot being fixed — rejected as the acceptance signal, kept as setup
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cross-check); parsing the *source* `/usr/share/cups/model/BR4150_2.PPD` in the
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image (proves packaging, not the job — rejected); a throwaway CUPS-side hook or
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debug logging (more moving parts than one file read — rejected).
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blind spot being fixed, and it is additionally wrong for Booleans — rejected as
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the acceptance signal, kept as setup cross-check); parsing the *source*
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`/usr/share/cups/model/BR4150_2.PPD` in the image (proves packaging, not the job
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— rejected); a throwaway CUPS-side hook or debug logging (more moving parts than
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one filter run — rejected).
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**D3 — Investigate before specifying the `TonerSaveMode` outcome.**
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Rationale: the change must not encode an unverified assumption. Task group 1
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@@ -92,6 +148,11 @@ does reach the job, the scenario as written stands. If it does not, the
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investigation result is added to this design and the scenario is reworded to the
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verified behaviour plus an explicit limitation note before the checkboxes for
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task group 2/3 are ticked.
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**Outcome (see investigation result above): the queue default does reach the
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job, so the scenario stands as written** — with one refinement: the observable
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for `TonerSaveMode=False` must be the emitted `*TonerSaveMode False` feature (or
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its absence of the toner-save call), *never* an `lpoptions -l` asterisk, which
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mis-renders Boolean options.
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Alternatives considered: writing the scenario as aspirational and letting the
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test fail until someone fixes it (leaves a red suite and an untrue spec —
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rejected); downgrading the scenario up front to "the PPD copy is written"
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@@ -112,18 +173,18 @@ the test checks by applying the documented `PRINTER_OPTIONS` example.
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## Risks / Trade-offs
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- The spool file is lifetime-bounded (retention) and the test container's job
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never reaches a printer, so the test must read the file soon after submission
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and tolerate `connection refused` state messages; if it races, the preferred
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per-job capture is `cupsfilter <sample.pdf>` inside the container with the
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same PPD, which produces the same PostScript text without a queue.
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- The original D2 risk ("the spool file is lifetime-bounded, so read it soon
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after submission") materialised as a hard blocker rather than a race: with an
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unreachable printer the filters never run, so there is no filtered spool to
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read at all. Mitigation is the `cupsfilter -p <ppd>` route now recorded in D2,
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which needs no queue and no printer.
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- `lpadmin -o` behaviour is option- and CUPS-version-specific; the test must
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state the CUPS version it was verified against so a future base-image bump
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does not silently reinterpret the assertion.
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- If the investigation finds the drop is a CUPS/driverd quirk with no image-side
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fix, the change still lands value (honest spec + regression guard) but leaves
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`TonerSaveMode` as a documented limitation; that outcome must be reported, not
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absorbed.
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state the CUPS version it was verified against (`2.4.2-3+deb12u9`) so a future
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base-image bump does not silently reinterpret the assertion.
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- `lpoptions -p <queue> -l` mis-renders Boolean PPD options (shows `*False` for a
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stored `True`), so a future maintainer may "fix" the wrong layer; the test
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header and the README note must say that the emitted PostScript is the
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authority for `TonerSaveMode`.
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- Boolean `TonerSaveMode` is the same option the draft presets tune, so a future
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preset change can mask a broken queue default; the job-level test deliberately
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submits a job *without* `print-quality`/preset attributes to keep the two
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