feat: Implement `azdo pipelines build tag list` command

[tmeckel]

Sub-issue of #276. Hardened spec — do not re-derive decisions. Mirrors az pipelines build tag list from the Azure CLI and the Python implementation at azure-dev-ops/azext_devops/dev/pipelines/build.py#L210-L218.

Command Description

List the tags currently attached to an Azure Pipelines build identified by its numeric build ID. The command returns a *[]string (the list of tag name strings). The output is a single-column table Tags, one row per tag.

GET https://dev.azure.com/{organization}/{project}/_apis/build/builds/{buildId}/tags?api-version=7.1-preview.3

Locked Decisions (do not re-derive)

#	Decision	Rationale
1	Use the vendored SDK method build.Client.GetBuildTags. Mock already generated at internal/mocks/build_client_mock.go.	Mandate: vendored API.
2	The build is identified by a positional BUILD argument ([ORGANIZATION/]PROJECT/BUILD). The BUILD segment must parse as a positive integer (no name resolution).	Mirrors cancel (#252) and queue (#253).
3	Parse the positional using util.ParseProjectTargetWithDefaultOrganization from internal/cmd/util/scope.go:183. The function returns a *Target with Organization, Project, Target fields, accepting 2- or 3-segment inputs.	Mirrors internal/cmd/pipelines/build/{cancel,queue}/ precedent.
4	The user is not required to pass a project; the project segment in the positional is optional. When omitted, the project is resolved from the default config.	Mirrors all other pipelines build leaves.
5	No additional flags beyond --json / --jq / --template. The build ID is the only input.	Mirrors az pipelines build tag list which is flagless aside from the build identifier.
6	Default output is a table. JSON output via --json passes the raw SDK result *[]string to opts.exporter.Write.	No view struct needed for a list of strings; mirrors the show-sibling convention.
7	A build with no tags returns an empty *[]string; the table emits zero rows; JSON emits []. No error.	Mirrors az pipelines build tag list behavior.
8	No --max-items cap. Build tag lists are short (typically < 20 entries) and the SDK does not paginate.	Mirrors az pipelines build tag list.
9	No new SDK client, no new helper, no new package beyond internal/cmd/pipelines/build/tag/list.	Mandate: minimal code.
10	Mock for GetBuildTags is already generated. Do not regenerate.	Verified at internal/mocks/build_client_mock.go.

Command Signature

azdo pipelines build tag list [ORGANIZATION/]PROJECT/BUILD
  [--json ...]

• cobra.ExactArgs(1) — args[0] → target (via util.ParseProjectTargetWithDefaultOrganization).
• The Target field is parsed as int; non-numeric / zero / negative values rejected with util.FlagErrorf.

Flags

Flag	Maps to	Notes
--json / --jq / --template	util.AddJSONFlags	JSON export

JSON Output Contract

Pass the raw SDK result *[]string to opts.exporter.Write. The result is a list of tag name strings. No view struct is required.

Caveat: the SDK returns *[]string (a pointer to a slice of strings). The exporter handles both nil and empty-slice cases by emitting null and [] respectively.

Table Output Contract

Mirrors transform_build_tags_output from _format.py (single column Tags). One row per tag in the SDK response. The table header is Tags (uppercase, single column).

Tags
release
nightly
v1.2.3

An empty SDK result produces a table with no rows (only the header).

Command Wiring

• Package path: internal/cmd/pipelines/build/tag/list
• Files:
  • list.go — NewCmd(ctx util.CmdContext) *cobra.Command + listOptions + runList. Cobra Use: "list [ORGANIZATION/]PROJECT/BUILD". Aliases: []string{"ls", "l"} to match the project convention.
  • list_test.go — table-driven gomock tests
• Update internal/cmd/pipelines/build/tag/tag.go to add list.NewCmd(ctx) to cmd.AddCommand(...). Update the Example block.
• Higher-level parents must already remain wired: pipelines → build → tag → list.

API Surface

Reuse the already-vendored client. No new SDK clients or mocks required.

• build.Client.GetBuildTags → Tags - Get (REST 7.1-preview.3)
• build.GetBuildTagsArgs struct: {Project *string, BuildId *int}.
• The method returns *[]string (the list of tag name strings).

Mock for GetBuildTags is already generated. No mock regeneration needed.

Reference Existing Patterns

• azure-dev-ops/azuredevops/azext_devops/dev/pipelines/build.py#L210-L218 — get_build_tags Python implementation.
• azure-dev-ops/azuredevops/azext_devops/dev/pipelines/commands.py — g.command('list', 'get_build_tags', table_transformer=transform_build_tags_output).
• azure-dev-ops/azuredevops/azext_devops/dev/pipelines/_format.py — transform_build_tags_output (single-column Tags table).
• internal/cmd/pipelines/build/cancel/cancel.go (feat: Implement azdo pipelines build cancel command #252) — primary target-resolution precedent: uses Use: "cancel [ORGANIZATION/]PROJECT/BUILD", cobra.ExactArgs(1), util.ParseProjectTargetWithDefaultOrganization. list is read-only, so the destructive confirmation flow is dropped.
• internal/cmd/pipelines/build/queue/queue.go (feat: Implement azdo pipelines build queue command #253) — secondary target-resolution precedent: uses the same parser and the same cobra.ExactArgs(1) validation.
• internal/cmd/boards/workitem/list/list_test.go:765-844 — setupFakeDeps / stub* fixture.
• internal/mocks/build_client_mock.go — mock for GetBuildTags (already generated).
• internal/azdo/factory.go:61 — ClientFactory().Build(...) accessor (reuse).
• internal/cmd/util/scope.go:183 — util.ParseProjectTargetWithDefaultOrganization (project-scoped parser).

References

• Tags - Get (REST 7.1-preview.3)
• az pipelines build tag list (Azure CLI reference for UX)
• Python extension source: azext_devops/dev/pipelines/build.py
• Python extension source: azext_devops/dev/pipelines/commands.py
• Python extension source: azext_devops/dev/pipelines/_format.py