Add agent session metadata tracking and reporting to control plane

[sestinj]

Summary by cubic

Adds agent session metadata tracking to the control plane. Collects git diff stats and a short conversation summary, sent after each turn and on shutdown.

• New Features
  • Added utilities: calculateDiffStats, extractSummary, getAgentIdFromArgs, postAgentMetadata.
  • Serve calls updateAgentMetadata after each agent turn and before graceful exit; failures are non-blocking and logged.
  • Metadata includes additions/deletions from current repo diff and the last assistant message (trimmed).
  • Added unit tests for metadata utilities.

^{Written for commit a1f1d55. Summary will update automatically on new commits.}

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[github-actions]

✅ Review Complete

Code Review Summary

⚠️ Continue configuration error. Please verify that the assistant exists in Continue Hub.

---

[cubic-dev-ai]

2 issues found across 4 files

Prompt for AI agents (all 2 issues)

Understand the root cause of the following 2 issues and fix them.


<file name="extensions/cli/src/util/metadata.ts">

<violation number="1" location="extensions/cli/src/util/metadata.ts:37">
`calculateDiffStats` skips legitimate additions whose content starts with `++` because the metadata filter treats any line beginning with `&quot;+++&quot;` as a header, so diff lines like `+++counter;` (an added `++counter;`) are ignored and the addition count becomes inaccurate.</violation>

<violation number="2" location="extensions/cli/src/util/metadata.ts:38">
Deletions of lines starting with `--` (or `---`) are treated as metadata due to the `line.startsWith(&quot;---&quot;)` check, so diff lines such as `---counter;`—which represent a real removal of `--counter;`—are skipped and the deletion count under-reports the true change size.</violation>
</file>

_{Reply to cubic to teach it or ask questions. Re-run a review with @cubic-dev-ai review this PR}

[cubic-dev-ai]

Deletions of lines starting with -- (or ---) are treated as metadata due to the line.startsWith("---") check, so diff lines such as ---counter;—which represent a real removal of --counter;—are skipped and the deletion count under-reports the true change size.

Prompt for AI agents

Address the following comment on extensions/cli/src/util/metadata.ts at line 38:

<comment>Deletions of lines starting with `--` (or `---`) are treated as metadata due to the `line.startsWith(&quot;---&quot;)` check, so diff lines such as `---counter;`—which represent a real removal of `--counter;`—are skipped and the deletion count under-reports the true change size.</comment>

<file context>
@@ -0,0 +1,167 @@
+    // Skip diff metadata lines (@@, +++, ---, diff, index, etc.)
+    if (
+      line.startsWith(&quot;+++&quot;) ||
+      line.startsWith(&quot;---&quot;) ||
+      line.startsWith(&quot;@@&quot;) ||
+      line.startsWith(&quot;diff &quot;) ||
</file context>

Suggested change

	line.startsWith("---") ||
	line.startsWith("--- ") ||

[cubic-dev-ai]

calculateDiffStats skips legitimate additions whose content starts with ++ because the metadata filter treats any line beginning with "+++" as a header, so diff lines like +++counter; (an added ++counter;) are ignored and the addition count becomes inaccurate.

Prompt for AI agents

Address the following comment on extensions/cli/src/util/metadata.ts at line 37:

<comment>`calculateDiffStats` skips legitimate additions whose content starts with `++` because the metadata filter treats any line beginning with `&quot;+++&quot;` as a header, so diff lines like `+++counter;` (an added `++counter;`) are ignored and the addition count becomes inaccurate.</comment>

<file context>
@@ -0,0 +1,167 @@
+  for (const line of lines) {
+    // Skip diff metadata lines (@@, +++, ---, diff, index, etc.)
+    if (
+      line.startsWith(&quot;+++&quot;) ||
+      line.startsWith(&quot;---&quot;) ||
+      line.startsWith(&quot;@@&quot;) ||
</file context>

Suggested change

	line.startsWith("+++") ||
	line.startsWith("+++ ") ||