feat(cli): add --format flag for pretty, llm, and jsonl output

AGENTS.md

@@ -24,7 +24,11 @@ channels, members, etc.
 
 ## Key Files
 
-- **`slack_cli/__main__.py`** — Canonical CLI source. Entry point is `main()`, exposed as the `slack-cli` console script.
+- **`slack_cli/__main__.py`** — Canonical CLI source. Entry point is `main()`, exposed as the `slack-cli` console script. Supports three output formats via `-f/--format`:
+  - `pretty` (default) — ANSI/tree layout with URLs, for humans.
+  - `llm` — token-efficient text (no ANSI/URLs, grouped by channel+date, threads indented).
+  - `jsonl` — one JSON object per message; includes raw `ts`, `channel_id`, `user_id`.
+  Renderers are `render_pretty` / `render_llm` / `render_jsonl`; `cmd_messages` builds the display list once and dispatches.
 - **`pyproject.toml`** — Python packaging metadata. Declares `slack-cli` console script entry point and `dfindexeddb` dependency.
 - **`docs/indexeddb-format.md`** — Documents the on-disk format: LevelDB layer, IndexedDB databases, Blink value encoding, and the full Redux state schema with field-level detail.
 - **`scripts/analyze_structure.py`** — Introspects the live IndexedDB and dumps database/object-store/record-type info plus Redux state key schemas. Re-run this when the data format changes and update the docs accordingly.

slack_cli/__main__.py

@@ -218,6 +218,7 @@ def cmd_messages(
     count: int,
     unread_only: bool = False,
     since: datetime | None = None,
+    output_format: str = "pretty",
 ):
     """Print Messages From Slack State"""
     messages_store = state.get("messages", {})
@@ -389,6 +390,14 @@ def cmd_messages(
         for reply in replies:
             display.append((reply, 1))
 
+    # Select Format-Specific Renderer
+    renderers = {
+        "pretty": render_pretty,
+        "llm": render_llm,
+        "jsonl": render_jsonl,
+    }
+    renderer = renderers[output_format]
+
     # Print Last N Messages (Count depth=0 Entries Only)
     if len(display) > 0:
         # Walk Backwards to Find the Cutoff That Includes `count` Roots
@@ -405,6 +414,11 @@ def cmd_messages(
     else:
         visible = []
 
+    renderer(visible, display, domain, unread_only, since)
+
+
+def render_pretty(visible, display, domain, unread_only, since):
+    """Human-Friendly Terminal Output — ANSI, Rules, Tree Glyphs"""
     # ANSI Palette
     dim = "\033[90m"
     ts_color = "\033[90m"
@@ -525,6 +539,134 @@ def cmd_messages(
     print(f"--- Showing {root_count} of {total_roots} {label} ---")
 
 
+def render_llm(visible, display, domain, unread_only, since):
+    """Token-Efficient Text Output for LLM Consumption
+
+    Groups by channel, then by date. Drops ANSI, URLs, tree glyphs, and
+    repeated channel/date headers. Thread replies use 2-space indent.
+    """
+    # Group Visible Rows Into (Channel, Root+Replies) Blocks
+    # Walk the flat `visible` list, pairing each depth=0 row with the
+    # depth=1 rows that follow it until the next root.
+    blocks: list[tuple[str, dict, list[dict]]] = []
+    current_root: dict | None = None
+    current_replies: list[dict] = []
+    current_channel: str = ""
+    for msg, depth in visible:
+        if depth == 0:
+            if current_root is not None:
+                blocks.append((current_channel, current_root, current_replies))
+            current_root = msg
+            current_replies = []
+            current_channel = msg.get("channel", "")
+        else:
+            current_replies.append(msg)
+    if current_root is not None:
+        blocks.append((current_channel, current_root, current_replies))
+
+    # Emit Blocks — Channel Header on Change, Date Header on Change
+    last_channel: str | None = None
+    last_date: str | None = None
+
+    def fmt_row(msg: dict, indent: str = "") -> str:
+        if msg.get("ellipsis"):
+            skipped = msg.get("skipped")
+            if skipped:
+                inner = f"[… {skipped} earlier repl{'y' if skipped == 1 else 'ies'}]"
+            else:
+                inner = "[… older replies]"
+            return f"{indent}{inner}"
+        hm = msg["dt"].strftime("%H:%M")
+        subtype = f" [{msg['subtype']}]" if msg.get("subtype") else ""
+        user = msg.get("user", "?")
+        text = msg.get("text", "")
+        # Inline Single-Line Text; Indent Continuation Lines
+        lines = text.split("\n") if text else [""]
+        head = f"{indent}{hm} {user}{subtype}:"
+        if lines == [""]:
+            return head
+        if len(lines) == 1:
+            return f"{head} {lines[0]}"
+        cont_indent = indent + "  "
+        return head + " " + lines[0] + "".join(f"\n{cont_indent}{ln}" for ln in lines[1:])
+
+    for channel, root, replies in blocks:
+        # Channel Header on Change
+        if channel != last_channel:
+            if last_channel is not None:
+                print()
+            print(f"== #{channel} ==")
+            last_channel = channel
+            last_date = None
+
+        # Date Header on Change (Per Channel)
+        root_date = root["dt"].strftime("%Y-%m-%d")
+        if root_date != last_date:
+            print(root_date)
+            last_date = root_date
+
+        # Root Row — Annotate Orphans and Thread Reply Counts Inline
+        if root.get("is_orphan"):
+            hm = root["dt"].strftime("%H:%M")
+            print(f"  {hm} (orphan — parent uncached):")
+        else:
+            suffix = ""
+            if root.get("is_thread_parent"):
+                # Count Actual Shown Replies (Excluding Ellipsis Marker)
+                n = sum(1 for r in replies if not r.get("ellipsis"))
+                suffix_note = f" thread ({n}):"
+            else:
+                suffix_note = ""
+            # Splice Thread Note Before the Colon Added by fmt_row
+            row = fmt_row(root, indent="  ")
+            if suffix_note and row.endswith(":"):
+                row = row[:-1] + suffix_note
+            elif suffix_note and ": " in row:
+                # Multi-Line or Inline-Text Case — Insert Before First ": "
+                head, rest = row.split(": ", 1)
+                row = head + suffix_note + " " + rest
+            print(row)
+
+        # Replies — 4-Space Indent
+        for reply in replies:
+            print(fmt_row(reply, indent="    "))
+
+    # Footer — Compact Summary
+    root_count = sum(1 for _, d in visible if d == 0)
+    total_roots = sum(1 for _, d in display if d == 0)
+    label = "unread" if unread_only else "msgs"
+    since_note = f" since={since.strftime('%Y-%m-%d %H:%M')}" if since else ""
+    print(f"-- {root_count}/{total_roots} {label}{since_note} --")
+
+
+def render_jsonl(visible, display, domain, unread_only, since):
+    """One JSON Object Per Message — Structured Consumption"""
+    for msg, depth in visible:
+        if msg.get("ellipsis"):
+            obj = {
+                "type": "ellipsis",
+                "depth": depth,
+                "skipped": msg.get("skipped"),
+            }
+        else:
+            obj = {
+                "type": "message",
+                "depth": depth,
+                "channel": msg.get("channel"),
+                "channel_id": msg.get("channel_id"),
+                "ts": msg.get("ts"),
+                "thread_ts": msg.get("thread_ts"),
+                "datetime": msg["dt"].isoformat() if msg.get("dt") else None,
+                "user": msg.get("user"),
+                "user_id": msg.get("user_id"),
+                "subtype": msg.get("subtype") or None,
+                "text": msg.get("text"),
+                "is_thread_parent": msg.get("is_thread_parent", False),
+                "is_orphan": msg.get("is_orphan", False),
+            }
+        print(json.dumps(obj, ensure_ascii=False, default=str))
+
+
 def cmd_channels(state: dict):
     """List Channels With Message Counts"""
     messages_store = state.get("messages", {})
@@ -591,6 +733,10 @@ def main():
         "--dump", nargs="?", const="slack_state.json",
         help="Dump full state to JSON file"
     )
+    parser.add_argument(
+        "-f", "--format", choices=["pretty", "llm", "jsonl"], default="pretty",
+        help="Output format: pretty (default, ANSI/tree), llm (token-efficient text), jsonl (one JSON per message)"
+    )
     args = parser.parse_args()
 
     # Find and Decode the Blob
@@ -613,7 +759,7 @@ def main():
         cmd_channels(state)
     else:
         cmd_messages(state, args.channels, args.exclude_channels,
-                     args.count, args.unread, args.since)
+                     args.count, args.unread, args.since, args.format)
 
 
 if __name__ == "__main__":