fix: warn when agent services share a Foundry agent name

[huimiu]

Fixes #8872

Problem

In an azure.yaml with multiple host: azure.ai.agent services, two or more services can carry the same agent name. Foundry uses the agent name as an agent's unique identifier, so deploying both services creates/updates the same Foundry agent — they silently overwrite each other, and azd gives no signal.

Example from the issue: services toolbox-agent-2 and toolbox-agent-4 both set name: toolbox-agent-2.

Change

azd deploy/azd up now emits a non-blocking warning when two or more azure.ai.agent services resolve to the same Foundry agent name, naming the colliding services so the user can give each a unique name. Deploy still proceeds.

• findDuplicateAgentNames scans the azure.ai.agent services, resolves each via project.LoadAgentDefinition (covers the unified inline shape, the legacy config shape, and a legacy on-disk agent.yaml), groups the azure.yaml service keys by resolved agent name, and returns groups shared by ≥2 services (deterministically sorted). Services that aren't hosted agents, can't be resolved, or have an empty name are skipped.
• warnDuplicateAgentNames prints one yellow warning per group to stderr via output.WithWarningFormat, matching the existing init / legacy-shape warning style.
• Wired into predeployHandler behind a new duplicateAgentNameWarnOnce sync.Once, so the project-wide scan warns at most once per process even though the handler fires per agent service — mirroring the existing developerRBACOnce pattern.

Tests

TestFindDuplicateAgentNames covers: no services, unique names, the issue's two-service collision, a three-way collision, multiple groups sorted by agent name, and non-agent-host / unresolvable services being skipped, plus a nil-project case.

Validation

From cli/azd/extensions/azure.ai.agents: gofmt clean, go build ./..., go vet ./internal/cmd/, and the full internal/cmd test suite all pass.

[github-actions]

📋 Prioritization Note

Thanks for the contribution! The linked issue isn't in the current milestone yet.
Thank you for logging this issue; our team is reviewing it. If you need urgent prioritization, tag @RickWinter and @kristenwomack to let us know.

[Copilot]

Pull request overview

Adds a deploy-time, non-blocking warning in the azure.ai.agents extension when multiple azure.ai.agent services in a project resolve to the same Foundry agent name, helping users avoid silent overwrites in Foundry.

Changes:

• Scan azure.ai.agent services during pre-deploy to detect duplicate resolved Foundry agent names and emit a warning once per extension process.
• Add unit tests covering duplicate grouping, deterministic sorting, and skip conditions.
• Document the new warning behavior in the extension changelog.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
cli/azd/extensions/azure.ai.agents/internal/cmd/listen.go	Adds duplicate-agent-name detection and emits an advisory warning during predeploy (once per process).
cli/azd/extensions/azure.ai.agents/internal/cmd/listen_test.go	Adds table-driven tests for duplicate detection and skip cases.
cli/azd/extensions/azure.ai.agents/CHANGELOG.md	Notes the new warning behavior for azd deploy / azd up.

[jongio]

One convention item: the new sort.* calls can be switched to slices.Sort/slices.SortFunc to match the Go 1.26+ patterns used throughout this extension. See inline suggestion for the specific change.