max / quasi

Say what the filler had left over when it stops early "the filler stopped before the residual did" names the symptom and nothing else, and the symptom has one interesting cause: the residual holds a structural op the fill program has no instruction for, which is the two halves of one shape disagreeing about its structure rather than anything a request did. The message now says how far the walk got and what the first op left is.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01P8ostB2UmZJGj5WjSHRSot

Author: Max Johnson <me@maxj.phd> · 2026-09-08 22:38 UTC

Signed with PGP, not checked

Commit: 06a9c02242b569a7ee30de2784d0f791f6662583

Parent: f9863c4

3 files changed, +76 insertions, -5 deletions

M Cargo.lock +4 -4

			@@ -6314,6 +6314,10 @@
6314	6314		"winnow 1.0.4",
6315	6315		]
6316	6316
	6317	+	[[patch.unused]]
	6318	+	name = "synckit-client"
	6319	+	version = "0.10.0"
	6320	+
6317	6321		[[patch.unused]]
6318	6322		name = "kberg"
6319	6323		version = "0.1.0"
			@@ -6330,10 +6334,6 @@
6330	6334		name = "tagtree"
6331	6335		version = "0.4.1"
6332	6336
6333		-	[[patch.unused]]
6334		-	name = "synckit-client"
6335		-	version = "0.10.0"
6336		-
6337	6337		[[patch.unused]]
6338	6338		name = "quasi-type"
6339	6339		version = "0.1.3"

M crates/quasi-bench/src/dispatched.rs +53

			@@ -68,6 +68,47 @@
68	68		}
69	69		}
70	70
	71	+	declare! {
	72	+	/// The same listing with the dispatch written inline, and a cell after it.
	73	+	///
	74	+	/// MNW's feed is this shape rather than the one below: the dispatch sits in
	75	+	/// the loop body of the table's own shape, with cells either side of it and
	76	+	/// an `activate` on the row. The version below puts the row in a shape of
	77	+	/// its own, which gives the dispatch a scope to itself and a position at
	78	+	/// the end -- so it never exercised what follows an arm.
	79	+	#[staged]
	80	+	pub(crate) shape inline_listing(items: &[Item]) -> Node;
	81	+
	82	+	table {
	83	+	column "Name" {
	84	+	width Fill;
	85	+	}
	86	+	column "Price" {
	87	+	width Content;
	88	+	}
	89	+	column "Date" {
	90	+	width Content;
	91	+	}
	92	+
	93	+	for item in items.iter() {
	94	+	cells {
	95	+	cell at "Name" item.name.clone();
	96	+
	97	+	given item.free {
	98	+	true -> cell at "Price" "" {
	99	+	token Tag::badge("Free").tone(layout::Tone::Success);
	100	+	}
	101	+	otherwise -> cell at "Price" price(item);
	102	+	}
	103	+
	104	+	cell at "Date" item.name.clone();
	105	+
	106	+	activate to get "/i/{item.name}" navigating;
	107	+	}
	108	+	}
	109	+	}
	110	+	}
	111	+
71	112		declare! {
72	113		/// One row. The price cell is a dispatch, not a pair of guards.
73	114		///
			@@ -106,6 +147,18 @@
106	147		///
107	148		/// The old failure stated as a test: exactly one case reached the residual
108	149		/// and the rest were gone, so a residual holding only one is the bug.
	150	+	/// A dispatch with a cell after it, which is the feed's shape.
	151	+	#[test]
	152	+	fn an_arm_is_followed_by_the_cells_written_after_it() {
	153	+	let webview = Webview::new();
	154	+	let residual = quasi_webview::stage::derive(&Webview::new(), inline_listing_staged);
	155	+	let rows = items(&[true, false, true]);
	156	+	assert_eq!(
	157	+	webview.fragment(&inline_listing(&rows)),
	158	+	inline_listing_serve(&residual, &rows),
	159	+	);
	160	+	}
	161	+
109	162		#[test]
110	163		fn both_cases_reach_the_residual() {
111	164		let residual = residual();

M crates/quasi-router/src/stage.rs +19 -1

			@@ -684,6 +684,17 @@
684	684		Arms(Cow<'static, [Cow<'static, [Op]>]>),
685	685		}
686	686
	687	+	/// What one op is, for a message a reader can act on.
	688	+	fn describe(op: &Op) -> &'static str {
	689	+	match op {
	690	+	Op::Lit(_) => "a literal",
	691	+	Op::Hole { .. } => "a hole",
	692	+	Op::Branch(_) => "a branch, which a guard makes",
	693	+	Op::Loop(_) => "a loop, which a `for` makes",
	694	+	Op::Arms(_) => "a dispatch, which `given` or a settling setting makes",
	695	+	}
	696	+	}
	697	+
687	698		/// A screen's markup with the request taken out of it.
688	699		///
689	700		/// # Why the instructions are borrowed or owned
			@@ -1173,7 +1184,14 @@
1173	1184		self.literals(out);
1174	1185		assert!(
1175	1186		self.at == self.ops.len(),
1176		-	"the filler stopped before the residual did"
	1187	+	"the filler stopped before the residual did: {} of {} ops walked, and \
	1188	+	the first one left is {}. A structural op left over means the residual \
	1189	+	holds a branch, a loop or a dispatch that the fill program has no \
	1190	+	instruction for, which is the two halves of one shape disagreeing \
	1191	+	about its structure rather than anything a request did.",
	1192	+	self.at,
	1193	+	self.ops.len(),
	1194	+	self.ops.get(self.at).map_or("nothing", describe),
1177	1195		);
1178	1196		}
1179	1197		}