diff --git a/packages/codev-upload/src/stats.ts b/packages/codev-upload/src/stats.ts
index d3370c3b6..8cde1c47e 100644
--- a/packages/codev-upload/src/stats.ts
+++ b/packages/codev-upload/src/stats.ts
@@ -17,6 +17,8 @@ export interface StatsMessage {
     role?: string
     modelID?: string
     providerID?: string
+    agent?: string
+    mode?: string
     cost?: number
     tokens?: {
       input?: number
@@ -89,6 +91,15 @@ export interface SessionStats {
   user_turns: number
   subagents: number
   files_changed: number
+  // Assistant messages per agent (build, plan, ...) in the top-level session.
+  agents: Record<string, number>
+  // Skill uses by name: skill tool calls and reads of a skill's SKILL.md,
+  // subagents included.
+  skills: Record<string, number>
+  // Skills whose SKILL.md the session wrote, by name.
+  skills_created: Record<string, number>
+  // Distinct files read or modified, by lowercased extension (".ts").
+  file_extensions: Record<string, number>
   totals: Usage
   buckets: Bucket[]
 }
@@ -132,6 +143,12 @@ export function buildSessionStats(input: StatsInput): SessionStats | null {
     user_turns: input.messages.filter(isUserPrompt).length,
     subagents: input.descendants.length,
     files_changed: files.size,
+    agents: tally(
+      input.messages.flatMap((message) =>
+        message.info.role === "assistant" ? [message.info.agent || message.info.mode || ""].filter(Boolean) : [],
+      ),
+    ),
+    ...fileBreakdowns([...input.messages, ...input.descendants.flat()]),
     totals,
     buckets: [...buckets.values()].sort((a, b) => a.hour.localeCompare(b.hour) || a.model.localeCompare(b.model)),
   }
@@ -240,6 +257,57 @@ function toolEdit(part: FinishedToolPart): { added: number; deleted: number; fil
   return undefined
 }
 
+// Skill and file breakdowns from every settled tool call. Log-analytics
+// parity (ai-hub-worker's skills and file_paths enrichers): a read of
+// <name>/SKILL.md is a skill use, a write to it creates the skill, and file
+// extensions cover files read as well as modified.
+function fileBreakdowns(messages: StatsMessage[]) {
+  const skills: string[] = []
+  const created = new Set<string>()
+  const touched = new Set<string>()
+  for (const part of messages.flatMap((message) => message.parts.filter(isFinishedToolPart))) {
+    const input = part.state.input ?? {}
+    if (part.tool === "skill") {
+      const name = textValue(input.name)
+      if (name) skills.push(name)
+      continue
+    }
+    const paths = toolPaths(part)
+    for (const path of paths) touched.add(path)
+    for (const name of paths.flatMap((path) => SKILL_FILE.exec(path)?.slice(1, 2) ?? [])) {
+      if (part.tool === "read") skills.push(name)
+      else if (part.state.status === "completed") created.add(name)
+    }
+  }
+  return {
+    skills: tally(skills),
+    skills_created: tally([...created]),
+    file_extensions: tally([...touched].map(extensionOf).filter(Boolean)),
+  }
+}
+
+const SKILL_FILE = /[/\\]([^/\\]+)[/\\]SKILL\.md$/
+const FILE_TOOLS = new Set(["read", "edit", "write"])
+
+function toolPaths(part: FinishedToolPart): string[] {
+  const input = part.state.input ?? {}
+  if (FILE_TOOLS.has(part.tool)) return [textValue(input.filePath)].filter(Boolean)
+  if (part.tool !== "apply_patch" || !Array.isArray(part.state.metadata?.files)) return []
+  return (part.state.metadata.files as { filePath?: unknown }[]).map((file) => textValue(file.filePath)).filter(Boolean)
+}
+
+function extensionOf(path: string): string {
+  const name = path.split(/[/\\]/).pop() ?? ""
+  const dot = name.lastIndexOf(".")
+  return dot > 0 ? name.slice(dot).toLowerCase() : ""
+}
+
+function tally(values: string[]): Record<string, number> {
+  const counts: Record<string, number> = {}
+  for (const value of values) counts[value] = (counts[value] ?? 0) + 1
+  return counts
+}
+
 function countDiffLines(diff: string): { added: number; deleted: number } {
   const lines = diff.split("\n")
   return {
diff --git a/packages/codev-upload/test/stats.test.ts b/packages/codev-upload/test/stats.test.ts
index 91b09f071..c079ea544 100644
--- a/packages/codev-upload/test/stats.test.ts
+++ b/packages/codev-upload/test/stats.test.ts
@@ -135,6 +135,37 @@ describe("buildSessionStats", () => {
     expect(stats?.files_changed).toBe(2)
   })
 
+  test("breaks sessions down by agent, skill, created skill, and file extension", () => {
+    const stats = buildSessionStats({
+      id: "ses1",
+      origin: "local",
+      project: "proj",
+      messages: [
+        assistant(T0, { agent: "build" }, [
+          tool("skill", "completed", { input: { name: "pdf" } }),
+          tool("read", "completed", { input: { filePath: "/home/u/.codev/skills/xlsx/SKILL.md" } }),
+          tool("read", "completed", { input: { filePath: "/p/src/App.TSX" } }),
+          tool("edit", "completed", { input: { filePath: "/p/src/app.tsx" } }),
+          tool("write", "completed", { input: { filePath: "/p/.codev/skills/deploy/SKILL.md" } }),
+          // A denied write creates nothing, but the file was still touched.
+          tool("write", "error", { input: { filePath: "/p/.codev/skills/broken/SKILL.md" } }),
+          tool("apply_patch", "completed", {
+            metadata: { files: [{ filePath: "/p/README" }, { filePath: "/p/a.py" }] },
+          }),
+        ]),
+        assistant(T0 + 1000, { agent: "plan" }),
+        assistant(T0 + 2000, { agent: "build" }),
+      ],
+      descendants: [[assistant(T0 + 1500, { agent: "explore" }, [tool("skill", "error", { input: { name: "pdf" } })])]],
+    })
+    // Subagent turns belong to the subagent, not the session's mode.
+    expect(stats?.agents).toEqual({ build: 2, plan: 1 })
+    expect(stats?.skills).toEqual({ pdf: 2, xlsx: 1 })
+    expect(stats?.skills_created).toEqual({ deploy: 1 })
+    // Distinct files touched per extension, case-folded; extensionless files are skipped.
+    expect(stats?.file_extensions).toEqual({ ".md": 3, ".tsx": 2, ".py": 1 })
+  })
+
   test("a session without messages yields nothing", () => {
     expect(buildSessionStats({ id: "s", origin: "local", project: "p", messages: [], descendants: [] })).toBeNull()
   })