A look with a blank in its pattern addresses, file:N selects the line, and a miss is said, logged and reads back empty

Round 6: look calc.py:/return a/ was a word search, since a blank ended the address; calc.py:99 past the end focused the file and said nothing; and /look still read back the pane before a miss. A pattern after the colon may now hold blanks; file:N selects the line, newline included, as acme's does; a line past the end opens and focuses nothing; and every miss (no match, a bad address, a line past the end) says so, logs err <serial> look: why, keeps the selection, and leaves look reading back empty. Documented, with file:0/re/ for the first match, since acme evaluates the address from the file's dot. Five goldens change: a look at file:N now selects the line.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

10 files changed, 108 insertions, 37 deletions

diff --git a/.agents/skills/pardes-9p/SKILL.md b/.agents/skills/pardes-9p/SKILL.md
index d34fa8b3..1be910c1 100644
--- a/.agents/skills/pardes-9p/SKILL.md
+++ b/.agents/skills/pardes-9p/SKILL.md
@@ -54,7 +54,9 @@ $m/README     the served guide, worth reading first
 $m/index      one line per pane: serial, kind (text|term|pdf|image), dirty flag, name
 $m/status     pid, version, panes
 $m/look       write a line = a right click on it at the active pane (file:/re/, file:#n, :/re/
-              select by address, as acme's look; a miss changes nothing)
+              select by address, as acme's look, from the file's dot: file:0/re/ for the
+              first match; file:N selects the line; a miss changes nothing, logs err, and
+              look reads back empty)
 $m/exec       write a line = a middle click: an editor command word, or a shell line
 $m/pane/<n>/pty/run   write one line, read `exit N` + its output, or `busy` / `error ...`, on the same open:
               exec 3<>$m/pane/$n/pty/run; echo make >&3; cat <&3
diff --git a/docs/fs.md b/docs/fs.md
index f6516ea1..a489e1ea 100644
--- a/docs/fs.md
+++ b/docs/fs.md
@@ -309,12 +309,18 @@ not the hits buffer it opened.
 
 A look takes acme's addresses after a colon (editors/acme/look.c:450): a
 line written to `look` as `file:/re/`, `file:#n`, `file:$` or any address
-opens (or finds) the file and selects what the address names, evaluated
-from its dot; `:addr` does the same in the pane itself. `file:12` and
-`file:12:5` stay line and column. A bare `/re/` is a path, as in acme, and
-failing that a search for its text. A look that finds nothing, or an
-address that does not evaluate, says so on the message row and changes
-nothing: no buffer opens and the selection stays.
+opens (or finds) the file and selects what the address names. **The
+address is evaluated from the file's dot**, as acme's is: `file:/re/`
+finds the next match after the current selection, not the first in the
+file. For the first, start at the top: `file:0/re/` (or `file:#0/re/`).
+`:addr` does the same in the pane itself, and a pattern may hold blanks
+(`calc.py:/return a/`). `file:12` selects line 12, its newline included,
+as acme's does; `file:12:5` puts the caret at line 12, column 5. A bare
+`/re/` is a path, as in acme, and failing that a search for its text. A
+look that finds nothing, an address that does not evaluate, or a line past
+the file's end (`calc.py:99`) says so on the message row and in the log
+(`err <serial> look: ...`), focuses and opens nothing, keeps the
+selection, and leaves `look` reading back empty.
 
 `/pane/<n>/name` reads the pane's file name (a terminal's directory) and
 writing it renames the buffer; a relative name resolves against the pane's
diff --git a/src/look.zig b/src/look.zig
index 020aacb8..6cf01dd2 100644
--- a/src/look.zig
+++ b/src/look.zig
@@ -1142,14 +1142,49 @@ pub fn followPdfLink(p: *Pardes, id: usize, probe: *const panes.Pdf.WordProbe) v
     }
 }
 
+/// A look that found nothing: said on the message row, logged as an `err`
+/// record, and marked so that /look reads back nothing (ninep/ctl.zig run).
+fn missed(p: *Pardes, id: usize, comptime fmt: []const u8, args: anytype) void {
+    p.look_missed = true;
+    var said: [160]u8 = undefined;
+    const why = std.fmt.bufPrint(&said, fmt, args) catch "no match";
+    var msg: [176]u8 = undefined;
+    p.setMessage(id, std.fmt.bufPrint(&msg, "Look: {s}", .{why}) catch "Look: no match");
+    const serial = if (p.panes[id]) |pane| pane.serial else 0;
+    var rec: [200]u8 = undefined;
+    pardes.ctlfs.events.notePath(p, "err", std.fmt.bufPrint(&rec, "{d} look: {s}", .{ serial, why }) catch return);
+}
+
+/// After a look at `path:N` focused its pane: a line past the end focuses
+/// nothing, leaves no pane it opened, and is a miss; a bare line number
+/// selects the line, its newline included, as acme's does.
+fn settleLine(p: *Pardes, id: usize, path: []const u8, at: Spot, before: usize, opened: ?usize) void {
+    const shown = p.panes[p.active] orelse return;
+    const f = if (shown.file) |*file| file else return;
+    if (at.line > panes.File.nlines(p.gpa, f)) {
+        if (opened) |free| p.removePane(free, null) catch {};
+        if (p.panes[before] != null) p.active = before;
+        return missed(p, id, "{s} has no line {d}", .{ path, at.line });
+    }
+    if (at.line > 0 and at.col == 0 and at.end_line == 0) {
+        const start = modal.lineStartOffset(f.content, at.line - 1);
+        const next = std.mem.indexOfScalarPos(u8, f.content, start, '\n');
+        const end = if (next) |i| i + 1 else f.content.len;
+        @import("ninep/pane.zig").setDot(shown, .{ .q0 = @intCast(start), .q1 = @intCast(end) });
+    }
+}
+
 /// `file:addr` or `:addr`, acme's look.c:450-543: a colon followed by an
 /// address character (addr.c:28, isaddrc) that is not a line spot this
 /// parser already reads (`file:12`, `file:12:5`). Not a URL.
 fn addressed(tok: []const u8) ?struct { path: []const u8, expr: []const u8 } {
     if (std.mem.indexOf(u8, tok, "://") != null) return null;
-    if (std.mem.indexOfAny(u8, tok, " \t") != null) return null;
     const colon = std.mem.indexOfScalar(u8, tok, ':') orelse return null;
     const expr = tok[colon + 1 ..];
+    // A written look is a whole line: the path has no blanks, but a
+    // pattern in the address may (`calc.py:/return a/`).
+    if (std.mem.indexOfAny(u8, tok[0..colon], " \t") != null) return null;
+    if (std.mem.indexOfAny(u8, expr, " \t") != null and std.mem.indexOfAny(u8, expr, "/?") == null) return null;
     if (expr.len == 0 or std.mem.indexOfScalar(u8, "0123456789+-/$.#,;", expr[0]) == null) return null;
     if (std.ascii.isDigit(expr[0])) {
         const pl = parsePathLine(tok);
@@ -1177,12 +1212,10 @@ fn lookAddress(p: *Pardes, id: usize, path: []const u8, expr: []const u8) void {
     if (path.len > 0 and (f.output != null or !std.mem.endsWith(u8, f.path, std.fs.path.basename(path)))) return;
     var a: Addr = .{ .text = f.content, .lim = null, .expr = expr };
     const r = a.address(ninep_pane.dotOf(pane)) orelse {
-        var said: [128]u8 = undefined;
-        return p.setMessage(id, std.fmt.bufPrint(&said, "Look: {s}", .{a.err}) catch "Look: bad address");
+        return missed(p, id, "{s}", .{a.err});
     };
     if (a.i < expr.len or r.q0 > r.q1) {
-        var said: [128]u8 = undefined;
-        return p.setMessage(id, std.fmt.bufPrint(&said, "Look: {s}", .{if (r.q0 > r.q1) "addresses out of order" else "bad address syntax"}) catch "Look: bad address");
+        return missed(p, id, "{s}", .{if (r.q0 > r.q1) "addresses out of order" else "bad address syntax"});
     }
     clearNavigationSelection(p, pane);
     ninep_pane.setDot(pane, r);
@@ -1209,6 +1242,10 @@ pub fn lookAt(p: *Pardes, id: usize, operand: []const u8) void {
     if (comptime pdf_enabled) if (panes.Pdf.lookSection(p, id, pl.path, pl.at)) return;
     var realbuf: [4096]u8 = undefined;
     const found = resolveLookTarget(p, id, txt, &realbuf);
+    // A line past the end of an open pane is a miss (the target's line is
+    // already clamped, so the one written is asked).
+    if (found == .pane and found.pane.id < MAX_PANES) if (p.panes[found.pane.id]) |shown| if (shown.file) |*f| if (pl.at.line > panes.File.nlines(p.gpa, f))
+        return missed(p, id, "{s} has no line {d}", .{ trimmed, pl.at.line });
     // A miss changes nothing, the selection included; anything else starts
     // from a clean one.
     if (found != .none) clearNavigationSelection(p, pane);
@@ -1219,10 +1256,7 @@ pub fn lookAt(p: *Pardes, id: usize, operand: []const u8) void {
                 p.reportError(id, "search", err);
                 return;
             };
-            if (rows == 0) {
-                var said: [96]u8 = undefined;
-                return p.setMessage(id, std.fmt.bufPrint(&said, "Look: no match for \"{s}\"", .{@import("Messages.zig").clip(trimmed, 48)}) catch "Look: no match");
-            }
+            if (rows == 0) return missed(p, id, "no match for \"{s}\"", .{@import("Messages.zig").clip(trimmed, 48)});
             clearNavigationSelection(p, pane);
             const at = pane.search_row;
             _ = searchStep(p, id, 1);
@@ -1235,8 +1269,10 @@ pub fn lookAt(p: *Pardes, id: usize, operand: []const u8) void {
         .pane => |t| {
             if (t.id >= MAX_PANES) return;
             const target = p.panes[t.id] orelse return;
+            const before = p.active;
             clearNavigationSelection(p, target);
             focusPaneLine(p, t.id, t.at, .center);
+            settleLine(p, id, trimmed, t.at, before, null);
         },
         .url => |u| if (u.len <= 256) p.emit(.{ .open_link = .from(u) }),
         .dir => |dir| {
@@ -1267,20 +1303,30 @@ pub fn lookAt(p: *Pardes, id: usize, operand: []const u8) void {
                 exec.placeDoc(p, id, free, nt);
                 return;
             };
+            // An open pane on this path too short for the line: a miss that
+            // touches nothing.
+            if (openPaneTarget(p, target.path, target.at)) |open| if (p.panes[open.pane.id].?.file) |*f|
+                if (target.at.line > panes.File.nlines(p.gpa, f))
+                    return missed(p, id, "{s} has no line {d}", .{ target.path, target.at.line });
             // focus an existing pane on this path (rescrolled), else open
-            if (focusPaneByPath(p, target.path, target.at)) return;
-            const free = p.freeSlot() orelse return p.reportError(id, "look", error.NoPaneSlots);
-            const nt = panes.File.open(p, free, target.path, target.at.line) catch |err|
-                return p.reportError(id, "look", err);
-            if (target.at.col > 0) nt.body.cur_col = @intCast(target.at.col - 1);
-            exec.placeDoc(p, id, free, nt);
-            layout.compute(p);
-            nt.file.?.scroll -|= @max(1, p.rects[free].h -| BOX_H) / 2;
-            if (target.at.end_line != 0) {
-                const centered = nt.file.?.scroll;
-                selectSpan(p, nt, target.at);
-                nt.file.?.scroll = centered;
+            const before = p.active;
+            var opened: ?usize = null;
+            if (!focusPaneByPath(p, target.path, target.at)) {
+                const free = p.freeSlot() orelse return p.reportError(id, "look", error.NoPaneSlots);
+                const nt = panes.File.open(p, free, target.path, target.at.line) catch |err|
+                    return p.reportError(id, "look", err);
+                if (target.at.col > 0) nt.body.cur_col = @intCast(target.at.col - 1);
+                exec.placeDoc(p, id, free, nt);
+                layout.compute(p);
+                nt.file.?.scroll -|= @max(1, p.rects[free].h -| BOX_H) / 2;
+                if (target.at.end_line != 0) {
+                    const centered = nt.file.?.scroll;
+                    selectSpan(p, nt, target.at);
+                    nt.file.?.scroll = centered;
+                }
+                opened = free;
             }
+            settleLine(p, id, target.path, target.at, before, opened);
         },
         .image => |target| {
             if (focusPaneByPath(p, target.path, .{})) return;
diff --git a/src/ninep/ctl.zig b/src/ninep/ctl.zig
index b11692e0..edf81cd9 100644
--- a/src/ninep/ctl.zig
+++ b/src/ninep/ctl.zig
@@ -69,10 +69,13 @@ fn run(p: *Pardes, id: usize, exec: bool, text: []const u8) void {
     const before = Serials.snapshot(p);
     // An exec answers the pane it went to: a command pane it reused, or
     // the terminal it typed into.
+    p.look_missed = false;
     const went: ?usize = if (exec) pardes.exec.execute(p, id, text) else blk: {
         look.lookAt(p, id, text);
         break :blk null;
     };
+    // A look that found nothing answers nothing, not the pane before it.
+    if (!exec and p.look_missed) return;
     const after = Serials.snapshot(p);
     var created = false;
     for (after.list[0..after.len]) |serial| if (std.mem.indexOfScalar(u32, before.list[0..before.len], serial) == null) {
@@ -892,6 +895,18 @@ test "a look takes acme's :addr and file:addr, and a miss changes nothing" {
     try testing.expectEqual(Status.ok, wr(p, look_node, "foo\n").reply.status);
     var own: [16]u8 = undefined;
     try testing.expectEqualStrings(try std.fmt.bufPrint(&own, "{d}\n", .{serial}), rd(p, look_node, 0, 64).bytes);
+    // A pattern with a blank in it; 0/re/ searches from the top, whatever dot is.
+    try testing.expectEqual(Status.ok, wr(p, look_node, ":/foo y/\n").reply.status);
+    try testing.expectEqualStrings("          6          11 ", rd(p, dot, 0, 64).bytes);
+    try testing.expectEqual(Status.ok, wr(p, look_node, try std.fmt.bufPrint(&line, "{s}:0/foo/\n", .{path})).reply.status);
+    try testing.expectEqualStrings("          0           3 ", rd(p, dot, 0, 64).bytes);
+    // file:N selects the line; a line past the end moves nothing and reads back empty.
+    try testing.expectEqual(Status.ok, wr(p, look_node, try std.fmt.bufPrint(&line, "{s}:2\n", .{path})).reply.status);
+    try testing.expectEqualStrings("         12          16 ", rd(p, dot, 0, 64).bytes);
+    try testing.expectEqual(Status.ok, wr(p, look_node, try std.fmt.bufPrint(&line, "{s}:99\n", .{path})).reply.status);
+    try testing.expectEqualStrings("         12          16 ", rd(p, dot, 0, 64).bytes);
+    try testing.expectEqualStrings("", rd(p, look_node, 0, 64).bytes);
+    try testing.expectStringStartsWith(p.panes[0].?.msg[0..p.panes[0].?.msg_len], "Look: ");
 }
 
 test "exec runs a builtin at the pane and records the pane it acted on" {
diff --git a/src/pardes.zig b/src/pardes.zig
index 55c8de8e..a85c97ab 100644
--- a/src/pardes.zig
+++ b/src/pardes.zig
@@ -4102,6 +4102,8 @@ pub const Pardes = struct {
     last_click: ?struct { id: usize, on_tag: bool, row: i32, col: i32, ms: i64 } = null,
     /// A B1 chord's edits share the undo point it took (mouse.zig).
     chord_hold: bool = false,
+    /// The look just run found nothing (look.zig missed).
+    look_missed: bool = false,
     look_hover_wait: ?look.LookHoverWait = null,
     look_hover_preview: ?look.LookHoverPreview = null,
     pdf_hover_preview: if (pdf_enabled) ?look.PdfWordPreview else void = if (pdf_enabled) null else {},
diff --git a/test/snapshots/look-center.golden b/test/snapshots/look-center.golden
index 3eaa819b..e5db101e 100644
--- a/test/snapshots/look-center.golden
+++ b/test/snapshots/look-center.golden
@@ -1,4 +1,4 @@
-== snap center-open grid=150x31 cursor=7,12
+== snap center-open grid=150x31 cursor=15,12
 |Newcol Joincol Find Grep Help Changelog Tutor Dump NextColor Debug Exit
 |   New Tty Find Grep Joincol Delcol                                           New Tty Find Grep Joincol Delcol
 |   /tmp/pardes-snap/look-center/cwd Tty+bash Save Mode Filter Collapse Del    /tmp/pardes-snap/look-center/cwd Tty+bash Save Mode Filter Collapse Del
@@ -19,7 +19,7 @@
 |   /tmp/pardes-snap/look-center/cwd Tty+bash Save Mode Filter Collapse Del
 |  ls
 |  big.txt
-== snap center-dedup grid=150x31 cursor=7,12
+== snap center-dedup grid=150x31 cursor=15,12
 |7:    145 line 145
 |8:    146 line 146                                                                big.txt:150 big.txt:2
 |9:    147 line 147
@@ -30,7 +30,7 @@
 |14:    152 line 152
 |15:    153 line 153
 |16:    154 line 154
-== snap center-clamp grid=150x31 cursor=7,8
+== snap center-clamp grid=150x31 cursor=13,8
 |7:      1 line 1
 |8:      2 line 2                                                                  big.txt:150 big.txt:2
 |9:      3 line 3
diff --git a/test/snapshots/look-file-1col.golden b/test/snapshots/look-file-1col.golden
index f70f787b..45f9f20f 100644
--- a/test/snapshots/look-file-1col.golden
+++ b/test/snapshots/look-file-1col.golden
@@ -1,4 +1,4 @@
-== snap file-open-1col grid=100x31 cursor=7,19
+== snap file-open-1col grid=100x31 cursor=14,19
 |Newcol Joincol Find Grep Help Changelog Tutor Dump NextColor Debug Exit
 |   New Tty Find Grep Joincol Delcol
 |   /tmp/pardes-snap/look-file-1col/cwd Tty+bash Save Mode Filter Collapse Del
diff --git a/test/snapshots/look-file.golden b/test/snapshots/look-file.golden
index 19b7899d..f0690264 100644
--- a/test/snapshots/look-file.golden
+++ b/test/snapshots/look-file.golden
@@ -1,4 +1,4 @@
-== snap file-open grid=150x31 cursor=7,12
+== snap file-open grid=150x31 cursor=14,12
 |Newcol Joincol Find Grep Help Changelog Tutor Dump NextColor Debug Exit
 |   New Tty Find Grep Joincol Delcol                                           New Tty Find Grep Joincol Delcol
 |   /tmp/pardes-snap/look-file/cwd Tty+bash Save Mode Filter Collapse Del      /tmp/pardes-snap/look-file/cwd Tty+bash Save Mode Filter Collapse Del
@@ -32,7 +32,7 @@
 |9: 0-0 d,#152019, 1-1 d,#0d1410, 2-6 #59675c,#0d1410, 7-13 #e5eee5,#0d1410, 14-74 d,#0d1410, 75-75 d,#608269, 76-76 d,#0d1410, 77-149 #e5eee5,#0d1410,
 |10: 0-0 d,#152019, 1-1 d,#0d1410, 2-6 #59675c,#0d1410, 7-13 #e5eee5,#0d1410, 14-74 d,#0d1410, 75-75 d,#608269, 76-76 d,#0d1410, 77-149 #e5eee5,#0d1410,
 |11: 0-0 d,#152019, 1-1 d,#0d1410, 2-6 #59675c,#0d1410, 7-13 #e5eee5,#0d1410, 14-74 d,#0d1410, 75-75 d,#608269, 76-76 d,#0d1410, 77-149 #e5eee5,#0d1410,
-|12: 0-0 d,#608269, 1-1 d,#0d1410, 2-6 #616f64,#0d1410,b 7-13 #e5eee5,#0d1410, 14-74 d,#0d1410, 75-75 d,#608269, 76-76 d,#0d1410, 77-149 #e5eee5,#0d1410,
+|12: 0-0 d,#608269, 1-1 d,#0d1410, 2-6 #616f64,#0d1410,b 7-14 #f5f7ee,#3c614a, 15-74 d,#0d1410, 75-75 d,#608269, 76-76 d,#0d1410, 77-149 #e5eee5,#0d1410,
 |13: 0-0 d,#152019, 1-1 d,#0d1410, 2-6 #59675c,#0d1410, 7-13 #e5eee5,#0d1410, 14-74 d,#0d1410, 75-75 d,#608269, 76-76 d,#0d1410, 77-149 #e5eee5,#0d1410,
 |14: 0-0 d,#152019, 1-1 d,#0d1410, 2-6 #59675c,#0d1410, 7-13 #e5eee5,#0d1410, 14-74 d,#0d1410, 75-75 d,#608269, 76-76 d,#0d1410, 77-149 #e5eee5,#0d1410,
 |15: 0-0 d,#152019, 1-1 d,#0d1410, 2-6 #59675c,#0d1410, 7-13 #e5eee5,#0d1410, 14-74 d,#0d1410, 75-75 d,#608269, 76-76 d,#0d1410, 77-149 #e5eee5,#0d1410,
diff --git a/test/snapshots/lookloaded.golden b/test/snapshots/lookloaded.golden
index 8883609a..48dffe49 100644
--- a/test/snapshots/lookloaded.golden
+++ b/test/snapshots/lookloaded.golden
@@ -1,4 +1,4 @@
-== snap file-open grid=100x31 cursor=7,12
+== snap file-open grid=100x31 cursor=14,12
 |Newcol Joincol Find Grep Help Changelog Tutor Dump NextColor Debug Exit
 |   New Tty Find Grep Joincol Delcol                  New Tty Find Grep Joincol Delcol
 |   /tmp/pardes-snap/lookloaded/cwd Tty+bash Save M   /tmp/pardes-snap/lookloaded/cwd Tty+bash Save M
@@ -22,7 +22,7 @@
 == snap removed grid=100x31 cursor=54,7
 |5:                                                     rm big.txt; echo GO''NE
 |6:    /tmp/pardes-snap/lookloaded/cwd/big.txt Save Tt  GONE
-== snap look-noFS grid=100x31 cursor=7,12
+== snap look-noFS grid=100x31 cursor=14,12
 |7:      5 line 5
 |8:      6 line 6                                         big.txt:10
 |9:      7 line 7
diff --git a/test/snapshots/rsearch.golden b/test/snapshots/rsearch.golden
index 8312e1bc..ccf8067b 100644
--- a/test/snapshots/rsearch.golden
+++ b/test/snapshots/rsearch.golden
@@ -18,7 +18,7 @@
 |23:    /tmp/pardes-snap/rsearch/cwd/+Search Save Tty Collapse Del LocationsConfig
 |24:      1 code.txt:4:1-8
 |25:      2 pick two words
-== snap path-open grid=210x31 cursor=7,16
+== snap path-open grid=210x31 cursor=16,16
 |13:    /tmp/pardes-snap/rsearch/cwd/sub/dep.txt Save Tty Collapse Del
 |14:      1 d1
 |15:      2 d2