dap-observer

You have that debugger running. Breakpoints set. But.... what are the values on the stack right now?? How could you possibly learn that? Well, this will do it.

dap-observer is a small, tool that does one thing -- it connects to a DAP session and shows the values of the variables while the debugger steps through the code.

Now, for this to work you need a multiplexer for the DAP. Otherwise your editor/IDE gets all of the fun. https://github.com/dap-mux/dap-mux is one of those.

The observer only ever joins an existing multiplexer session. It does not spawn the adapter or manage the session.

# terminal 1 — adapter + mux
python -m debugpy.adapter --host 127.0.0.1 --port 5678
dap-mux --attach 5678 --headless -p 5679

# terminal 2 — Helix drives the session
hx sieve.py    # set a breakpoint, then :debug-remote 127.0.0.1:5679 launch

# terminal 3 — the observer (this crate)
dap-observer                # connects to 127.0.0.1:5679 by default
dap-observer 5680           # custom port
dap-observer host:port      # custom host + port

Step in the editor. The observer refreshes its variable tree whenever execution stops at a breakpoint.

Watches

Deeply-nested variables get lost when the tree re-roots on every step. Press w on a variable to pin it as a watch: it appears in a ── watched ── section pinned to the top of the list and is re-evaluated against the current frame on every stop, so you don't have to re-navigate to it. Press w again on the variable (or on its watched row) to unpin it. A watch that falls out of scope stays pinned and shows (unavailable) until it resolves again.

Keys

key	action
j / k (or ↓/↑)	move selection
l / h (or →/←)	expand / collapse the selected node (fetches children lazily on expand)
Enter / Space	toggle expand/collapse
w	pin / unpin the selected variable as a watch
g / G	jump to top / bottom
q / Esc	quit (clean disconnect, terminal restored)

Headless mode

--headless skips the TUI and prints each stop to stdout. Useful for testing.