add/update --report corrupts title and title-only update clears report link

[CrowBe]

Environment

• tasks-axi 0.2.5
• Fedora Linux

Reproduction

mkdir -p /tmp/tasks-axi-report-repro/data
cp .tasks.toml /tmp/tasks-axi-report-repro/.tasks.toml
printf "## In flight\n\n## Queued\n\n## Done\n" > /tmp/tasks-axi-report-repro/data/backlog.md
cd /tmp/tasks-axi-report-repro

tasks-axi add repro-report-link "original title" --repo firstmate --report data/repro-report-link/report.md
tasks-axi show repro-report-link --full

tasks-axi update repro-report-link --title "renamed title"
tasks-axi show repro-report-link --full

tasks-axi update repro-report-link --report data/repro-report-link/report.md
tasks-axi show repro-report-link --full

Actual

1. add ... --report ... renders title: original title data/repro-report-link/report.md while also setting links: "report:data/repro-report-link/report.md".
2. update --title "renamed title" changes the title but unexpectedly clears the report link (links: none).
3. Restoring the report with update --report ... renders title: renamed title data/repro-report-link/report.md and restores the link.

Expected

--report should update only the report link, and --title should update only the title. Repeated independent mutations must preserve the other field.

Consumer investigation

This reproduces by invoking tasks-axi directly in an empty backlog. The dependent firstmate repository does not call tasks-axi add/update --report; its only report-bearing production call is tasks-axi done <id> --report <path>, so its invocation is not the cause.

[CrowBe]

Follow-up: the same corruption occurs on the exact production command family.

tasks-axi add done-report-fixture "done report title" --kind ship --repo firstmate --start
tasks-axi done done-report-fixture --report data/done-report-fixture/report.md --no-prune
tasks-axi show done-report-fixture --full

On 0.2.5 this renders title: done report title data/done-report-fixture/report.md plus links: "report:data/done-report-fixture/report.md". --no-prune only retains the done task so the result is inspectable; firstmate normally uses done --report ... --keep 0, which prunes it afterward. So firstmate is not constructing a malformed title, but tasks-axi done --report itself shares the link/title mutation defect.