Making a lane one row cost the thing a row was for. A clip stopped being a row,
so there was no longer any way to open a clip and see what was inside it, and
the inside of a drawing — the most ordinary thing in the document — became
reachable only by opening it as its own tab. This is that capability back,
from the root timeline, down as far as it goes.
An expanded lane opens exactly ONE clip: the selected one. Its own keys, then
the lanes and nodes of the symbol it places, then theirs, each mapped into this
ruler by the recursive walk that was already there. Twelve clips in a lane
still cost one row, and inspection costs one branch rather than twelve.
Two things that only showed up once it ran. The portal is chosen by the whole
LINEAGE of the selection and not by the selected id: selecting a shape inside
the clip — or the end of its span — is still working inside that clip, and
matching the id alone shut the portal the instant anything under it was
touched. And selecting now waits for the pointer to come UP, because selecting
on the way down re-drew the timeline before the gesture had said anything: it
shut the portal holding the lane being dragged INTO, out from under the
pointer.
A HELD clip opens too, which the old row walk never did either. `source-time`
is nil for a hold, so the walk stopped there and the contents of every drawing
were invisible from here. Its rows are shown across the hold — which is when
the node is on screen — and marked `:unmapped?`: no keys, and no draggable
edges, because a frozen clock gives no frame inside it a place on this ruler.
Refusing to place the keys is the honest half; refusing to show the rows was
not.
Double-clicking a clip opens the symbol it places as a tab, as double-clicking
the same symbol in the pool does. That was already written and had never once
run: the track captures the pointer for a slide, so the click and double-click
that follow are delivered to the track and never to the block. The track now
resolves them itself. Fixing the delivery exposed two more: `symbol/lineage`
reported a `parent cycle` for any id in a symbol with NO nodes, because a
one-element chain is longer than zero nodes — and opening a symbol left the
selection pointing into the symbol being left, which the breadcrumb and the
inspector then tried to resolve. The editor unmounted. Both are fixed where
they were wrong, and the browser test asserts the editor is still standing
afterwards.
Audio is a clip in a lane like everything else. A dropped sound lands in one
and is trimmed and moved by the same commands; a lane holds picture or sound
and not both, which is the explicit capability the model asked for rather than
a guess per frame. The refusal lives in the commands and not only in
validation, because placement claims time: `blank` would have deleted the
sound to make room for the picture and left a perfectly valid document behind.
What is in a lane of the open symbol is drawn as a lane; what is nested inside
a placed symbol is still flattened by `audio-tracks`, so no sound is on two
rows.
Everything that enters the timeline now enters a lane: a converted take, a
symbol brought in from another project, a sound. One rule answers where —
`lane-destination` — and every symbol is born with a lane for it to answer
with. An unaimed drop fills an EMPTY lane rather than taking an occupied one
nobody pointed at, because the alternative is trimming away what was there to
make room for what was dropped.
Shift during a clip-body drag means the other intention: put this node INSIDE
the symbol the clip under the pointer places, through `nest/move-node`, which
is what keeps the world transform and the root timing. Overlap cannot say
which of the two is meant — dropping on occupied time already means claiming
it — so the person says, and a label by the pointer says it back. The label
asks `nest/move-refusal`, the same check the command makes, so it cannot
promise what the drop would refuse. Today it refuses more than it allows:
both clips have to be on screen at one frame, which two clips in one lane
never are, and a held destination has no clock to move through at all.
`docs/lane-nesting-notes.md` argues that the second refusal is stronger than
the facts require and says what would settle it.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Now that a lane is generic, the obvious next move is to read a clip dropped on
another clip as "put it inside that symbol". It cannot mean that: dropping a
clip on occupied lane time already means it claims that time and trims the
incumbent. Structural nesting therefore needs an explicit affordance -- a grab
handle with `grab`/`grabbing` cursors, distinct from the body's temporal move
and the edges' trims -- and its drop must route through `nest/move-node`, which
preserves world transform and root timing, rather than through a weaker
`:parent` assignment that would make a drawing jump when it is rehoused.
The second half of the note is what expansion should be. One permanently
expanded row per lane clip is the vertical growth the one-row lane exists to
avoid, so an expanded lane shows exactly one portal: the currently selected
clip, swapped in place when the selection changes, not following the playhead.
The portal header is the structural drop target, sub-expanding it walks the
source symbol's lanes through the existing recursive root-time mapping, and
collapsed clips carry their instance-level keys as ticks. The cost of
inspection stays constant.
No lane-as-symbol type and no second ownership edge: the hierarchy is still
symbol, lane, clip, source symbol, its nodes. Lane membership owns time; a
symbol instance owns composition. Written before the interaction is built,
because the capability it protects is easy to lose by accident.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Your Name