Emit Depends and the 8 other dropped control fields

[dkijania]

Fixes #9

What

format_control_file emitted a hardcoded 12 fields, silently discarding Depends, Pre-Depends, Recommends, Suggests, Conflicts, Replaces, Provides, Vendor and Authors — even though the CLI accepts all nine, the values reach DebianControl, and content_verifier parses them back out of dpkg-deb -I in order to check them. build could not produce a package its own verify content was written to validate.

The failure was silent: build exited 0 and produced a well-formed .deb that installed fine wherever the dependencies happened to already be present, failing only on a clean target.

All the data already reached DebianControl, so the change is confined to the renderer.

Design calls

Optional fields are omitted when unset or empty, not emitted blank — dpkg has no use for a valueless Depends:.

The original twelve stay unconditional, blank or not, so packages built before this change keep byte-identical stanzas (Installed-Size: and Source: are routinely empty in practice). I deliberately left their empty-handling alone; changing it is unrelated scope with real breakage risk.

Lists join with ", ", which round-trips through content_verifier's split-on-comma-and-trim. One test pins exactly that, so the writer and reader can't drift apart again.

Field order follows Debian convention — Vendor/Authors after Maintainer, relationship fields after Installed-Size. Order is not semantically significant, and existing tests assert with contains.

Verification

7 new unit tests (this function had none): emission, omission when unset, empty-and-blank-only lists, entry trimming, the original twelve still unconditional, and the verifier round-trip.

Full CI gate green locally: cargo fmt --check, cargo clippy --all-targets -D warnings, cargo test --all-targets (51 lib + 9 integration), cargo test --doc.

Before/after on a real .deb, identical flags both times:

BEFORE (main)                    AFTER
  Package: mina-daemon             Package: mina-daemon
  Version: 1.2.3                   Version: 1.2.3
  Architecture: amd64              Architecture: amd64
  Maintainer: O(1)Labs ...         Maintainer: O(1)Labs ...
                                   Vendor: O(1)Labs
                                   Authors: O(1)Labs ...
  Section: base                    Section: base
  Priority: optional               Priority: optional
  Homepage: ...                    Homepage: ...
  Installed-Size:                  Installed-Size:
                                   Depends: libssl3, libgmp10, libgomp1
                                   Suggests: postgresql
                                   Conflicts: mina-devnet
                                   Replaces: mina-old
                                   Provides: mina
  Source:                          Source:
  Suite: stable                    Suite: stable
  Codename: bookworm               Codename: bookworm
  License: Apache-2.0              License: Apache-2.0

The BEFORE run exited 0 and produced a package with none of them.

Not in scope

Origin, Label and Breaks are not modelled at all (absent from DebianControl, not merely unemitted). mina emits all three, so they block a full migration of its build path — but they're additive features rather than this bug. The README's "Known limitation" section now names exactly those three.