Prepare azure.ai.agents 0.1.21-preview patch release

[Copilot]

Bumps azure.ai.agents from 0.1.20-preview to 0.1.21-preview with 11 user-facing changes across init, invoke, and run.

Version files

• version.txt and extension.yaml updated to 0.1.21-preview

Changelog entries

• Prompt for existing Foundry project when agent manifest has no model resources #7589 Fix azd ai agent init to prompt for an existing Foundry project when the manifest contains no model resources
• Fix agent init: container resource management and stale UX text #7607 Fix container resource selection to persist the chosen CPU/memory tier into agent.yaml and pre-select it on reruns; remove stale replica mention from post-init message
• azure.ai.agents - reduce noisy logs in azd ai agent init and redirect log output when --debug is used #7596 Reduce noisy output during azd ai agent init; internal log statements now route to the debug log file and only surface with --debug
• Clean up env vars automatically added to agent.yaml during init #7553 Stop writing AZURE_AI_PROJECT_ENDPOINT/AZURE_OPENAI_ENDPOINT to agent.yaml; azd ai agent run now translates AZURE_AI_* env vars to FOUNDRY_* equivalents for local agent processes
• feat: add validation to ensure manifest pointer is a file, not a directory #7576 Validate that the manifest path points to a file, not a directory
• [Agents extensions] Endpoint changes #7545 Update endpoint handling to use the latest Foundry agent service endpoints
• Print each SSE data object on its own line in invoke streaming output #7538 Fix azd ai agent invoke streaming to emit each SSE data object on its own line
• azure.ai.agents - filter out unsupported models and locations from init prompts #7415 Filter init prompts to only show locations and models supported for agent scenarios
• Fix init with project-id when agent.yaml doesn't contain a model resource #7410 Fix azd ai agent init --project-id when agent.yaml has no model resource
• [Agents extension] Detect agent manifest at cwd #7484 Auto-detect agent.manifest.yaml in the current directory and prompt to use it during azd ai agent init
• [Agents extension] Prompt user for protocols during "from code" flow #7464 Prompt for agent communication protocol (responses or invocations) during "from code" init flow

[Copilot]

Pull request overview

Prepares the azure.ai.agents extension for the 0.1.21-preview patch release by updating the extension version metadata and documenting the set of user-facing changes included in this release.

Changes:

• Bump extension version from 0.1.20-preview → 0.1.21-preview.
• Add 0.1.21-preview release notes to the extension changelog.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
cli/azd/extensions/azure.ai.agents/version.txt	Updates the extension’s version marker to 0.1.21-preview.
cli/azd/extensions/azure.ai.agents/extension.yaml	Updates extension manifest version to 0.1.21-preview.
cli/azd/extensions/azure.ai.agents/CHANGELOG.md	Adds the 0.1.21-preview (2026-04-09) section with links to the included PRs.

[jongio]

Looks good - all 11 referenced PRs are merged, version bumps are consistent across extension.yaml and version.txt, changelog entries follow existing formatting conventions, and no user-facing changes are missing from the release notes.

[github-actions]

📋 Prioritization Note

Thanks for the contribution! The linked issue isn't in the current milestone yet.
Review may take a bit longer — reach out to @rajeshkamal5050 or @kristenwomack if you'd like to discuss prioritization.

[trangevi]

/check-enforcer override