Backspace in a line's leading blanks goes back to the previous indent stop

helix's delete_char_backward dedents: when everything before the cursor on its
line is blank, it deletes back to the previous multiple of the indent width,
a whole unit when already on one (a tab before the cursor still goes alone).
pardes deleted one space, so O<backspace> under an indented line left three
of four, which is where helix-golf's function_into_class ended up.

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

3 files changed, 11 insertions, 0 deletions

diff --git a/test/hxcases/cases.jsonl b/test/hxcases/cases.jsonl
index 471d3a6c..cfd82cce 100644
--- a/test/hxcases/cases.jsonl
+++ b/test/hxcases/cases.jsonl
@@ -355,6 +355,11 @@
 {"name": "ins-enter-indent", "pane": "file", "text": "    foo\n", "keys": "A<ret>x<esc>"}
 {"name": "ins-backspace", "pane": "file", "text": "abc\n", "keys": "lli<backspace><esc>"}
 {"name": "ins-backspace-join", "pane": "file", "text": "ab\ncd\n", "keys": "ji<backspace><esc>"}
+{"name": "ins-backspace-indent-unit", "pane": "file", "text": "        x\n", "keys": "8li<backspace>"}
+{"name": "ins-backspace-indent-partial", "pane": "file", "text": "      x\n", "keys": "6li<backspace>"}
+{"name": "ins-backspace-indent-tab", "pane": "file", "text": "\t\tx\n", "keys": "2li<backspace>"}
+{"name": "ins-backspace-open-indent", "pane": "file", "text": "    ab\n", "keys": "O<backspace>"}
+{"name": "ins-backspace-after-text", "pane": "file", "text": "  a    x\n", "keys": "7li<backspace>"}
 {"name": "ins-ctrl-w", "pane": "file", "text": "one two\n", "keys": "A<C-w><esc>"}
 {"name": "ins-ctrl-w-col0-join", "pane": "file", "text": "ab\ncd\n", "keys": "ji<C-w><esc>"}
 {"name": "ins-alt-bs", "pane": "file", "text": "one two\n", "keys": "A<A-backspace><esc>"}
diff --git a/test/hxcases/goldens.jsonl b/test/hxcases/goldens.jsonl
index 516b2417..e258b485 100644
--- a/test/hxcases/goldens.jsonl
+++ b/test/hxcases/goldens.jsonl
@@ -355,6 +355,11 @@
 {"name":"ins-enter-indent","text":"    foo\n    x\n","mode":"normal","cursor":{"row":1,"col":5},"anchor":{"row":1,"col":5}}
 {"name":"ins-backspace","text":"ac\n","mode":"normal","cursor":{"row":0,"col":1},"anchor":{"row":0,"col":1}}
 {"name":"ins-backspace-join","text":"abcd\n","mode":"normal","cursor":{"row":0,"col":2},"anchor":{"row":0,"col":2}}
+{"name":"ins-backspace-indent-unit","text":"    x\n","mode":"insert","cursor":{"row":0,"col":4},"anchor":{"row":0,"col":4}}
+{"name":"ins-backspace-indent-partial","text":"    x\n","mode":"insert","cursor":{"row":0,"col":4},"anchor":{"row":0,"col":4}}
+{"name":"ins-backspace-indent-tab","text":"\tx\n","mode":"insert","cursor":{"row":0,"col":1},"anchor":{"row":0,"col":1}}
+{"name":"ins-backspace-open-indent","text":"\n    ab\n","mode":"insert","cursor":{"row":0,"col":0},"anchor":{"row":0,"col":0}}
+{"name":"ins-backspace-after-text","text":"  a   x\n","mode":"insert","cursor":{"row":0,"col":6},"anchor":{"row":0,"col":6}}
 {"name":"ins-ctrl-w","text":"one \n","mode":"normal","cursor":{"row":0,"col":4},"anchor":{"row":0,"col":4}}
 {"name":"ins-ctrl-w-col0-join","text":"cd\n","mode":"normal","cursor":{"row":0,"col":0},"anchor":{"row":0,"col":0}}
 {"name":"ins-alt-bs","text":"one \n","mode":"normal","cursor":{"row":0,"col":4},"anchor":{"row":0,"col":4}}
diff --git a/test/hxcases/parity-waivers.jsonl b/test/hxcases/parity-waivers.jsonl
index 39a6a7c9..ad24eaa9 100644
--- a/test/hxcases/parity-waivers.jsonl
+++ b/test/hxcases/parity-waivers.jsonl
@@ -11,3 +11,4 @@
 {"name":"comment-tab-indent","reason":"The terminal expands literal tabs to spaces before editing.","reference":{"name":"comment-tab-indent","text":"\t# alpha\n\t# beta\n","mode":"normal","cursor":{"row":1,"col":7},"anchor":{"row":0,"col":0}},"expected":{"name":"comment-tab-indent","text":"        # alpha\n        # beta\n","mode":"normal","cursor":{"row":1,"col":14},"anchor":{"row":0,"col":0}}}
 {"name":"comment-noeol","reason":"Terminal capture restores a trailing newline that the source omits.","reference":{"name":"comment-noeol","text":"# alpha","mode":"normal","cursor":{"row":0,"col":2},"anchor":{"row":0,"col":2}},"expected":{"name":"comment-noeol","text":"# alpha\n","mode":"normal","cursor":{"row":0,"col":2},"anchor":{"row":0,"col":2}}}
 {"name":"comment-only-blank","reason":"Terminal capture expands tabs and trims trailing blank rows.","reference":{"name":"comment-only-blank","text":"   \n\t\n","mode":"normal","cursor":{"row":1,"col":1},"anchor":{"row":0,"col":0}},"expected":{"name":"comment-only-blank","text":"   \n","mode":"normal","cursor":{"row":0,"col":3},"anchor":{"row":0,"col":0}}}
+{"name":"ins-backspace-indent-tab","reason":"The terminal expands literal tabs to spaces before editing.","reference":{"name":"ins-backspace-indent-tab","text":"\tx\n","mode":"insert","cursor":{"row":0,"col":1},"anchor":{"row":0,"col":1}},"expected":{"name":"ins-backspace-indent-tab","text":"              x\n","mode":"insert","cursor":{"row":0,"col":0},"anchor":{"row":0,"col":0}}}