Let the keyboard reach a tag's path, read-only

The tag's computed path, dirty marker and page were out of the keyboard's
reach: its cursor lived in the text after them. It now lives in the tag as
shown, as in acme where the name is ordinary text at the start of the tag, so
`0` goes to the line's start and motions select and yank the path. The path
stays read-only: an edit that would change it is refused and leaves the
cursor where it was, and typing into a file's path drafts a new name as a
click on it does. Sync moves the tag's positions when the prefix changes
length, so a rename or the dirty marker still never moves the cursor off the
text after it.

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

3 files changed, 19 insertions, 13 deletions

diff --git a/docs/design.typ b/docs/design.typ
index 8e5f7e6e..234c3692 100644
--- a/docs/design.typ
+++ b/docs/design.typ
@@ -790,12 +790,15 @@ A tag holds any number of lines; a pane's tag takes a row per line up to
 
 A pane's tag shows a live prefix (path, dirty marker, PDF page) before the text
 it owns, and that prefix is computed at every read, never stored
-(`tagline.tagPrefix`). The Text's coordinates are offsets into its own text
-alone, so a rename or a save never moves its cursor. The one translation
-point is the whole line as shown: render, the mouse, Look, Exec and the 9P
-`tag` file see prefix ++ text, while keyboard motions and edits see only the
-text. Editing the path is a separate draft (`Pane.prompt = .name`) committed
-by Enter, since a buffer's name is not text it owns.
+(`tagline.tagPrefix`). Everything sees the whole line as shown, prefix ++
+text: render, the mouse, Look, Exec, the 9P `tag` file and the keyboard,
+whose motions reach the path as acme's do. The prefix is read-only: an edit
+installs only what follows it, and one that would change it is refused
+(`edit.setEditText`, `Text.refused`). Because the prefix is computed, sync
+moves the tag's positions with it when its length changes (`Pane.tag_lead`).
+Editing the path is a separate draft (`Pane.prompt = .name`) committed by
+Enter, since a buffer's name is not text it owns; a click or a key typed
+into it starts one.
 
 The tag's text is bounded by `limits.max_tag_tail`: the 9P `tag` file and a
 dump reader refuse input that does not fit rather than truncating it.
diff --git a/docs/helix-keys.md b/docs/helix-keys.md
index 5edaccce..f46f5234 100644
--- a/docs/helix-keys.md
+++ b/docs/helix-keys.md
@@ -117,7 +117,7 @@ language-backend queries, and the shell pipe.
 | `Esc` (insert) | back to normal mode, cursor right after the insertion (no vim left-step) | | helix-verified |
 | `Enter` (normal) | acme **look** chord: EXPLICIT selection, else file-ish word under cursor | pardes-specific, keep (helix normal-mode Enter unbound). Covers helix `gf`. Implicit motion residue falls back to the cursor word | pardes-specific |
 | `Tab` (normal) | acme **execute** chord | pardes-specific, keep; explicit-selection rule as Enter | pardes-specific |
-| `:` (normal, body or tag) | in the body, focuses the pane's tag in normal mode at its remembered cursor (the first time, on `Save`); in the tag, goes back to the body; in a column or workspace tag, back to the active pane. The tag's normal and insert modes ARE the body's: every motion, selection, edit and undo works there, `0` meaning the start of the editable text. Tab runs the word under the cursor or the selection and Enter looks it up (in a column or workspace tag Enter runs it too), and either hands the keyboard back to the body first. Clicks choose a new cursor position and type into the tag. | Each tag keeps its own cursor during the session. Cursor, selections and undo are offsets in the tag's own text; the computed path/marker/page before it is seen by the mouse, Look and Exec but not by keyboard motions. File-name changes are staged as described in [editable tags](tags.md). | pardes-specific |
+| `:` (normal, body or tag) | in the body, focuses the pane's tag in normal mode at its remembered cursor (the first time, on `Save`); in the tag, goes back to the body; in a column or workspace tag, back to the active pane. The tag's normal and insert modes ARE the body's: every motion, selection, edit and undo works there, and `0` goes to the line's start, the path's. Tab runs the word under the cursor or the selection and Enter looks it up (in a column or workspace tag Enter runs it too), and either hands the keyboard back to the body first. Clicks choose a new cursor position and type into the tag. | Each tag keeps its own cursor during the session. The computed path/marker/page is reachable and yankable but read-only: an edit into it is refused, and typing into a file's path drafts a new name. File-name changes are staged as described in [editable tags](tags.md). | pardes-specific |
 | `Ctrl-w k` / `SPC w k` (pane with nothing above) | focuses its column's tag, then the workspace tag; with `ColumnTags` disabled it goes directly to the workspace. `Ctrl-w j` walks back to the panes, `Ctrl-w h`/`l` walk the column tags. Headers edit exactly as a pane tag does. | Column commands target that column's active pane, or its first pane when coming from elsewhere. Workspace and column text are independently editable and persist in dumps. See [editable tags](tags.md). | pardes-specific |
 | `Ctrl-w` + `h/j/k/l`/arrows | directional pane focus prefix — editor normal mode only | pardes' own window handling (helix window mode skipped, section C). Runs the SAME `Left`/`Down`/`Up`/`Right` builtins `SPC w h/j/k/l` runs; Raw **tty** mode forwards Ctrl-w to the child. Insert mode owns `Ctrl-w` = delete-word-back, so a tag being TYPED into swallows it; from a tag in normal mode it moves focus to the neighbour's BODY, as from a body, and from the top pane `Up` reaches the column and workspace tags | pardes-specific |
 | `Alt-n` | new terminal below (outside raw tty) | shadows helix `Alt-n` TS sibling-select — skipped anyway (tree-sitter) | pardes-specific |
diff --git a/docs/tags.md b/docs/tags.md
index 7c385c08..810ae010 100644
--- a/docs/tags.md
+++ b/docs/tags.md
@@ -51,11 +51,13 @@ a row per line, up to eight: a pane's tag leaves its body at least one row
 and a collapsed pane shows only the first line; the column and workspace
 tags take no more than a third of the screen, and the panes below move down
 to make room. The path, the dirty marker and a PDF's page at the start of a
-pane tag are computed, never stored: the tag's cursor, selections and undo
-live in the text after them, so a rename or a save never moves the cursor.
-The mouse still sees the whole line -- a sweep selects across the path and
-the commands, and Look and Exec work on either -- but the keyboard moves only
-in the tag's own text: `0` goes to its start, not the path's.
+pane tag are computed, never stored, and read-only. The keyboard reaches
+them as the mouse does: `0` goes to the line's start, the path's, as in
+acme, and motions select and yank across the path and the commands. An edit
+that would change them is refused and leaves the cursor where it was; typing
+into a file's path instead drafts a new name, as clicking it does. When they
+grow or shrink (a rename, the dirty marker, a PDF's page) the cursor keeps
+its place in the text after them.
 
 Left-click a tag or a header to type into it at the click, in insert mode;
 tags reveal the caret horizontally when text is wider than their column.
@@ -93,7 +95,8 @@ generated right-alignment padding. Intentionally customized spacing is kept.
 
 ## File names
 
-Clicking a file pane's name starts a draft of it, typed into at the click.
+Clicking a file pane's name, or typing into it from the tag, starts a draft
+of it, typed into where it was clicked or typed.
 Enter or Tab confirms the new buffer name; Escape or leaving the pane
 cancels the draft. Confirmation changes the
 buffer's save target and marks it unsaved. It does **not** rename, create or