feat: v2.6.0 — Chat UI composer (+ menu, project files, activity panel, permission mode, Stop), git on a workspace's extra folders (#70), long paste as a file (#68), S3 server mode (experimental)

Chat UI:
- Each Claude/Codex session keeps its own chat/terminal view; Settings only
  sets how new sessions open.
- Composer + menu: upload, project files and folders (#54, also dragged from
  the Files/Changes tree), context files, recent uploads, skills, plugins.
- Activity side panel (progress, outputs, files read, uploads, memory,
  skills, connectors) with a file preview; edited-file counts per turn.
- Permission-mode chip (Shift+Tab steps, read back from the pane:
  server/lib/pane-mode.js, GET|POST /api/run/:id/permission-mode).
- Stop (Esc) while the main agent works; the status is checked per agent
  (with session_id /api/agents ignores its status filter) and re-read every
  5 s while Stop shows.
- Dropped images shown in the conversation (GET /api/run/drop/:name, the
  requester's own drop dir), full-size viewer.
- A plain-text paste over 5,000 characters is attached as pasted-text.txt,
  so no prompt reaches tmux/argv limits (#68).

Changes panel: every /api/lanes/:id/git* route takes ?source=<lane_sources
id> (sourceFolder; ENOSOURCE otherwise) and a folder picker switches the
whole panel to a workspace's extra folder (#70).

Server mode S3 (one Linux user per account) — experimental, verified with
fake sudo plus a P6 managed-settings spike on a test account:
- member tmux listing runs in the background (cached, 15 s => unknown);
- transcript snapshot copy is async, chunked, temp file + rename;
- Express Layer patch only on Express 4;
- tmux capturePane/sendKey go to the member's own server.

Docs: the multi-user design moved in as docs/plans/server-mode/README.md
(the AgentHub-Server repo is gone); S3-PLAN P6 result; LANES/API/openapi.

server/openapi.js

@@ -432,12 +432,26 @@ function createOpenApiSpec() {
             },
             output: { type: "string", description: "Tool output text when type === tool_result." },
             is_error: { type: "boolean" },
+            diff: {
+              type: "object",
+              description:
+                "On the tool_result of a Write/Edit/MultiEdit: the lines it added and removed (Claude Code's structuredPatch; every line of a file it created).",
+              properties: {
+                added: { type: "integer" },
+                removed: { type: "integer" },
+              },
+            },
           },
         },
         TranscriptMessage: {
           type: "object",
           required: ["type", "content"],
           properties: {
+            stop_reason: {
+              type: "string",
+              description:
+                "Assistant lines only: why the model stopped — `end_turn` closes the turn, `tool_use` means a tool call (and more work) follows.",
+            },
             type: {
               type: "string",
               enum: ["user", "assistant", "session_event"],
@@ -1595,6 +1609,55 @@ function createOpenApiSpec() {
           },
         },
       },
+      "/api/sessions/{id}/outline": {
+        get: {
+          tags: ["Sessions"],
+          summary: "Get a session's plan, outputs and what it used",
+          description:
+            "Read off the session's successful tool calls (PostToolUse events) and its prompts: `progress` is its TaskCreate/TaskUpdate plan (a TodoWrite replaces it wholesale), `outputs` the paths it wrote or edited with Write/Edit/MultiEdit/NotebookEdit, `files` the paths it only read, `uploads` the files attached to its prompts through the composer (`/api/run/drop-*` paths), `memory` the Claude Code memory files (`.claude/**/memory/`) it read or wrote — the path lists newest first, a memory file in `memory` only —, `skills` the skills it invoked and `mcp` the MCP servers it called. Powers the activity panel of a Chat pane shown alone.",
+          operationId: "getSessionOutline",
+          parameters: [{ $ref: "#/components/parameters/SessionIdPath" }],
+          responses: {
+            200: {
+              description: "The session's outline",
+              content: {
+                "application/json": {
+                  schema: {
+                    type: "object",
+                    properties: {
+                      progress: {
+                        type: "array",
+                        items: {
+                          type: "object",
+                          properties: {
+                            id: { type: "string" },
+                            subject: { type: "string" },
+                            status: { type: "string" },
+                          },
+                        },
+                      },
+                      outputs: { type: "array", items: { type: "string" } },
+                      files: { type: "array", items: { type: "string" } },
+                      uploads: { type: "array", items: { type: "string" } },
+                      memory: { type: "array", items: { type: "string" } },
+                      skills: { type: "array", items: { type: "string" } },
+                      mcp: { type: "array", items: { type: "string" } },
+                    },
+                  },
+                },
+              },
+            },
+            404: {
+              description: "Session not found",
+              content: {
+                "application/json": {
+                  schema: { $ref: "#/components/schemas/ErrorResponse" },
+                },
+              },
+            },
+          },
+        },
+      },
       "/api/sessions/{id}/transcripts": {
         get: {
           tags: ["Sessions"],