tui: make tool-call arg width configurable via ZOT_TOOL_ARG_WIDTH (#70)

The tool-call header truncates the primary argument (path/command/query)
at a hardcoded 60 cells, which clips long queries on wide terminals.

Add a toolArgWidth() helper (mirroring CellAspectRatio) that reads the
ZOT_TOOL_ARG_WIDTH env var, defaulting to 60 and clamping to [20, 500]
so a stray value can never produce an unreadable header or an
out-of-range slice. Replace the three hardcoded 60s in ShortArgs.

Documented under Tool rendering in the README; covered by tests.

commit: 88a6f6e481904a71b78983e198b8351ed8fd4790
author: Graham Primm · 3mo ago · 2026-07-08 16:50 UTC
committer: GitHub · 3mo ago · 2026-07-08 16:50 UTC
parent: 30f9ca5
signature: GPG UnverifiedB5690EEEBB952194 The key is unknown
refs: tag: v0.2.67

3 files · +112 -6

M README.md +14 -0


@@ -619,6 +619,20 @@ ZOT_FLAT_TOOLS=0 zot # boxes, even if config.json says "flat"
619	619
620	620		Either way, theme colors still drive the rendering (the header uses your accent/foreground, output uses the tool-output color) and `ctrl+o` still expands a truncated result.
621	621
	622	+	### Tool arg width
	623	+
	624	+	The header line for a tool call shows the tool name plus a one-line summary of its primary argument — a `path`, a `command`, or a query. That summary is truncated to 60 cells by default (`web_answer What is the best architecture to implement resilience wit...`). On a wide terminal that can clip long queries more than you'd like, so set the `ZOT_TOOL_ARG_WIDTH` env var to raise (or lower) the limit:
	625	+
	626	+	```sh
	627	+	ZOT_TOOL_ARG_WIDTH=120 zot # allow up to 120 cells before truncating
	628	+	```
	629	+
	630	+	\| Value \| Effect \|
	631	+	\|---\|---\|
	632	+	\| unset (default) \| Truncate the arg summary at 60 cells. \|
	633	+	\| integer in `[20, 500]` \| Truncate at that many cells instead. \|
	634	+	\| anything else \| Ignored; falls back to the 60-cell default. \|
	635	+
622	636		## Compact input
623	637
624	638		By default a message you send renders as a padded, background-tinted bubble: a blank tinted row above and below the text, with a `▌` accent bar down the left. So even a one-line prompt occupies three rows. Set `compact_input` to collapse it to a single quiet `▌ your text` gutter line per wrapped row — no padding rows, no background tint.


@@ -619,6 +619,20 @@ ZOT_FLAT_TOOLS=0 zot # boxes, even if config.json says "flat"
619		619
620	Either way, theme colors still drive the rendering (the header uses your accent/foreground, output uses the tool-output color) and `ctrl+o` still expands a truncated result.	620		Either way, theme colors still drive the rendering (the header uses your accent/foreground, output uses the tool-output color) and `ctrl+o` still expands a truncated result.
621		621
		622	+	### Tool arg width
		623	+
		624	+	The header line for a tool call shows the tool name plus a one-line summary of its primary argument — a `path`, a `command`, or a query. That summary is truncated to 60 cells by default (`web_answer What is the best architecture to implement resilience wit...`). On a wide terminal that can clip long queries more than you'd like, so set the `ZOT_TOOL_ARG_WIDTH` env var to raise (or lower) the limit:
		625	+
		626	+	```sh
		627	+	ZOT_TOOL_ARG_WIDTH=120 zot # allow up to 120 cells before truncating
		628	+	```
		629	+
		630	+	\| Value \| Effect \|
		631	+	\|---\|---\|
		632	+	\| unset (default) \| Truncate the arg summary at 60 cells. \|
		633	+	\| integer in `[20, 500]` \| Truncate at that many cells instead. \|
		634	+	\| anything else \| Ignored; falls back to the 60-cell default. \|
		635	+
622	## Compact input	636		## Compact input
623		637
624	By default a message you send renders as a padded, background-tinted bubble: a blank tinted row above and below the text, with a `▌` accent bar down the left. So even a one-line prompt occupies three rows. Set `compact_input` to collapse it to a single quiet `▌ your text` gutter line per wrapped row — no padding rows, no background tint.	638		By default a message you send renders as a padded, background-tinted bubble: a blank tinted row above and below the text, with a `▌` accent bar down the left. So even a one-line prompt occupies three rows. Set `compact_input` to collapse it to a single quiet `▌ your text` gutter line per wrapped row — no padding rows, no background tint.

M packages/tui/view.go +35 -6


@@ -2131,19 +2131,48 @@ func toolResultBlock(th Theme, text string, width int, color int) []string {
2131	2131		return out
2132	2132		}
2133	2133
	2134	+	// defaultToolArgWidth is the number of cells the tool-call header
	2135	+	// truncates the primary argument (path/command/query) to when the
	2136	+	// ZOT_TOOL_ARG_WIDTH environment variable is unset or invalid.
	2137	+	const defaultToolArgWidth = 60
	2138	+
	2139	+	// toolArgWidth returns the maximum cell width for the truncated
	2140	+	// primary argument shown in a tool-call header. It defaults to
	2141	+	// defaultToolArgWidth but can be raised or lowered with the
	2142	+	// ZOT_TOOL_ARG_WIDTH environment variable, which is useful for wide
	2143	+	// terminals where the default clips long queries too aggressively.
	2144	+	// Values outside the sane range [20, 500] are ignored so a stray or
	2145	+	// malformed setting can never produce an unreadable header or an
	2146	+	// out-of-range slice.
	2147	+	func toolArgWidth() int {
	2148	+	v := strings.TrimSpace(os.Getenv("ZOT_TOOL_ARG_WIDTH"))
	2149	+	if v == "" {
	2150	+	return defaultToolArgWidth
	2151	+	}
	2152	+	n, err := strconv.Atoi(v)
	2153	+	if err != nil \|\| n < 20 \|\| n > 500 {
	2154	+	return defaultToolArgWidth
	2155	+	}
	2156	+	return n
	2157	+	}
	2158	+
2134	2159		// ShortArgs renders a tool call's arguments into a one-line
2135	2160		// suffix for the "tool name <args>" header. tool is the tool
2136	2161		// name so we can add shape-specific decorations: for read we
2137	2162		// append the requested line range (e.g. "path:1-200") pulled
2138	2163		// from the offset/limit args, which is useful context at a
2139	2164		// glance without expanding the result body. Other tools keep
2140		-	// the legacy "path or command, truncated at 60 cells" shape.
	2165	+	// the legacy "path or command, truncated" shape.
	2166	+	//
	2167	+	// The truncation width defaults to 60 cells but can be tuned via
	2168	+	// the ZOT_TOOL_ARG_WIDTH environment variable (see toolArgWidth).
2141	2169		//
2142	2170		// Exported because the interactive mode pre-populates the
2143	2171		// ToolCallView.Args field with this value as soon as the tool
2144	2172		// call is announced, so the live overlay's header matches what
2145	2173		// the finalised transcript will later render.
2146	2174		func ShortArgs(tool string, raw json.RawMessage) string {
	2175	+	width := toolArgWidth()
2147	2176		var v any
2148	2177		if err := json.Unmarshal(raw, &v); err != nil {
2149	2178		return ""

@@ -2152,8 +2181,8 @@ func ShortArgs(tool string, raw json.RawMessage) string {
2152	2181		if !ok {
2153	2182		b, _ := json.Marshal(v)
2154	2183		s := oneLineToolLabel(string(b))
2155		-	if len(s) > 60 {
2156		-	s = s[:57] + "..."
	2184	+	if len(s) > width {
	2185	+	s = s[:width-3] + "..."
2157	2186		}
2158	2187		return s
2159	2188		}

@@ -2167,8 +2196,8 @@ func ShortArgs(tool string, raw json.RawMessage) string {
2167	2196		if primary == "" {
2168	2197		b, _ := json.Marshal(v)
2169	2198		s := oneLineToolLabel(string(b))
2170		-	if len(s) > 60 {
2171		-	s = s[:57] + "..."
	2199	+	if len(s) > width {
	2200	+	s = s[:width-3] + "..."
2172	2201		}
2173	2202		return s
2174	2203		}

@@ -2193,7 +2222,7 @@ func ShortArgs(tool string, raw json.RawMessage) string {
2193	2222
2194	2223		// Truncate the primary arg leaving room for the suffix so the
2195	2224		// range stays visible even on absurdly long paths.
2196		-	max := 60 - len(suffix)
	2225	+	max := width - len(suffix)
2197	2226		if max < 10 {
2198	2227		max = 10
2199	2228		}

 	return out
 }
+// defaultToolArgWidth is the number of cells the tool-call header
+// truncates the primary argument (path/command/query) to when the
+// ZOT_TOOL_ARG_WIDTH environment variable is unset or invalid.
+const defaultToolArgWidth = 60
+// toolArgWidth returns the maximum cell width for the truncated
+// primary argument shown in a tool-call header. It defaults to
+// defaultToolArgWidth but can be raised or lowered with the
+// ZOT_TOOL_ARG_WIDTH environment variable, which is useful for wide
+// terminals where the default clips long queries too aggressively.
+// Values outside the sane range [20, 500] are ignored so a stray or
+// malformed setting can never produce an unreadable header or an
+// out-of-range slice.
+func toolArgWidth() int {
+	v := strings.TrimSpace(os.Getenv("ZOT_TOOL_ARG_WIDTH"))
+	if v == "" {
+		return defaultToolArgWidth
+	}
+	n, err := strconv.Atoi(v)
+	if err != nil || n < 20 || n > 500 {
+		return defaultToolArgWidth
+	}
+	return n
+}
 // ShortArgs renders a tool call's arguments into a one-line
 // suffix for the "tool name <args>" header. tool is the tool
 // name so we can add shape-specific decorations: for read we
 // append the requested line range (e.g. "path:1-200") pulled
 // from the offset/limit args, which is useful context at a
 // glance without expanding the result body. Other tools keep
-// the legacy "path or command, truncated at 60 cells" shape.
+// the legacy "path or command, truncated" shape.
+//
+// The truncation width defaults to 60 cells but can be tuned via
+// the ZOT_TOOL_ARG_WIDTH environment variable (see toolArgWidth).
 //
 // Exported because the interactive mode pre-populates the
 // ToolCallView.Args field with this value as soon as the tool
 // call is announced, so the live overlay's header matches what
 // the finalised transcript will later render.
 func ShortArgs(tool string, raw json.RawMessage) string {
+	width := toolArgWidth()
 	var v any
 	if err := json.Unmarshal(raw, &v); err != nil {
 		return ""
 	if !ok {
 		b, _ := json.Marshal(v)
 		s := oneLineToolLabel(string(b))
-		if len(s) > 60 {
+		if len(s) > width {
-			s = s[:57] + "..."
+			s = s[:width-3] + "..."
 		}
 		return s
 	}
 	if primary == "" {
 		b, _ := json.Marshal(v)
 		s := oneLineToolLabel(string(b))
-		if len(s) > 60 {
+		if len(s) > width {
-			s = s[:57] + "..."
+			s = s[:width-3] + "..."
 		}
 		return s
 	}
 	// Truncate the primary arg leaving room for the suffix so the
 	// range stays visible even on absurdly long paths.
-	max := 60 - len(suffix)
+	max := width - len(suffix)
 	if max < 10 {
 		max = 10
 	}

A packages/tui/view_tool_arg_width_test.go +63 -0

@@ -0,0 +1,63 @@
	1	+	package tui
	2	+
	3	+	import (
	4	+	"encoding/json"
	5	+	"strings"
	6	+	"testing"
	7	+	)
	8	+
	9	+	func TestToolArgWidthDefault(t *testing.T) {
	10	+	t.Setenv("ZOT_TOOL_ARG_WIDTH", "")
	11	+	if got := toolArgWidth(); got != defaultToolArgWidth {
	12	+	t.Fatalf("toolArgWidth() with unset env = %d, want %d", got, defaultToolArgWidth)
	13	+	}
	14	+	}
	15	+
	16	+	func TestToolArgWidthEnvOverride(t *testing.T) {
	17	+	t.Setenv("ZOT_TOOL_ARG_WIDTH", "120")
	18	+	if got := toolArgWidth(); got != 120 {
	19	+	t.Fatalf("toolArgWidth() = %d, want 120", got)
	20	+	}
	21	+	}
	22	+
	23	+	func TestToolArgWidthIgnoresInvalid(t *testing.T) {
	24	+	cases := []string{"nope", "0", "10", "501", "-5", "12.5"}
	25	+	for _, c := range cases {
	26	+	t.Setenv("ZOT_TOOL_ARG_WIDTH", c)
	27	+	if got := toolArgWidth(); got != defaultToolArgWidth {
	28	+	t.Fatalf("toolArgWidth() with %q = %d, want default %d", c, got, defaultToolArgWidth)
	29	+	}
	30	+	}
	31	+	}
	32	+
	33	+	func TestShortArgsTruncatesAtDefaultWidth(t *testing.T) {
	34	+	t.Setenv("ZOT_TOOL_ARG_WIDTH", "")
	35	+	long := strings.Repeat("a", 200)
	36	+	raw := json.RawMessage(`{"command":"` + long + `"}`)
	37	+	got := ShortArgs("web_answer", raw)
	38	+	if len(got) != defaultToolArgWidth {
	39	+	t.Fatalf("ShortArgs length = %d, want %d (%q)", len(got), defaultToolArgWidth, got)
	40	+	}
	41	+	if !strings.HasSuffix(got, "...") {
	42	+	t.Fatalf("ShortArgs should end with ellipsis, got %q", got)
	43	+	}
	44	+	}
	45	+
	46	+	func TestShortArgsRespectsWiderWidth(t *testing.T) {
	47	+	t.Setenv("ZOT_TOOL_ARG_WIDTH", "120")
	48	+	long := strings.Repeat("a", 200)
	49	+	raw := json.RawMessage(`{"command":"` + long + `"}`)
	50	+	got := ShortArgs("web_answer", raw)
	51	+	if len(got) != 120 {
	52	+	t.Fatalf("ShortArgs length = %d, want 120", len(got))
	53	+	}
	54	+	}
	55	+
	56	+	func TestShortArgsNoTruncationWhenShort(t *testing.T) {
	57	+	t.Setenv("ZOT_TOOL_ARG_WIDTH", "120")
	58	+	raw := json.RawMessage(`{"command":"short query"}`)
	59	+	got := ShortArgs("web_answer", raw)
	60	+	if got != "short query" {
	61	+	t.Fatalf("ShortArgs = %q, want %q", got, "short query")
	62	+	}
	63	+	}

@@ -0,0 +1,63 @@
	1	+	package tui
	2	+
	3	+	import (
	4	+	"encoding/json"
	5	+	"strings"
	6	+	"testing"
	7	+	)
	8	+
	9	+	func TestToolArgWidthDefault(t *testing.T) {
	10	+	t.Setenv("ZOT_TOOL_ARG_WIDTH", "")
	11	+	if got := toolArgWidth(); got != defaultToolArgWidth {
	12	+	t.Fatalf("toolArgWidth() with unset env = %d, want %d", got, defaultToolArgWidth)
	13	+	}
	14	+	}
	15	+
	16	+	func TestToolArgWidthEnvOverride(t *testing.T) {
	17	+	t.Setenv("ZOT_TOOL_ARG_WIDTH", "120")
	18	+	if got := toolArgWidth(); got != 120 {
	19	+	t.Fatalf("toolArgWidth() = %d, want 120", got)
	20	+	}
	21	+	}
	22	+
	23	+	func TestToolArgWidthIgnoresInvalid(t *testing.T) {
	24	+	cases := []string{"nope", "0", "10", "501", "-5", "12.5"}
	25	+	for _, c := range cases {
	26	+	t.Setenv("ZOT_TOOL_ARG_WIDTH", c)
	27	+	if got := toolArgWidth(); got != defaultToolArgWidth {
	28	+	t.Fatalf("toolArgWidth() with %q = %d, want default %d", c, got, defaultToolArgWidth)
	29	+	}
	30	+	}
	31	+	}
	32	+
	33	+	func TestShortArgsTruncatesAtDefaultWidth(t *testing.T) {
	34	+	t.Setenv("ZOT_TOOL_ARG_WIDTH", "")
	35	+	long := strings.Repeat("a", 200)
	36	+	raw := json.RawMessage(`{"command":"` + long + `"}`)
	37	+	got := ShortArgs("web_answer", raw)
	38	+	if len(got) != defaultToolArgWidth {
	39	+	t.Fatalf("ShortArgs length = %d, want %d (%q)", len(got), defaultToolArgWidth, got)
	40	+	}
	41	+	if !strings.HasSuffix(got, "...") {
	42	+	t.Fatalf("ShortArgs should end with ellipsis, got %q", got)
	43	+	}
	44	+	}
	45	+
	46	+	func TestShortArgsRespectsWiderWidth(t *testing.T) {
	47	+	t.Setenv("ZOT_TOOL_ARG_WIDTH", "120")
	48	+	long := strings.Repeat("a", 200)
	49	+	raw := json.RawMessage(`{"command":"` + long + `"}`)
	50	+	got := ShortArgs("web_answer", raw)
	51	+	if len(got) != 120 {
	52	+	t.Fatalf("ShortArgs length = %d, want 120", len(got))
	53	+	}
	54	+	}
	55	+
	56	+	func TestShortArgsNoTruncationWhenShort(t *testing.T) {
	57	+	t.Setenv("ZOT_TOOL_ARG_WIDTH", "120")
	58	+	raw := json.RawMessage(`{"command":"short query"}`)
	59	+	got := ShortArgs("web_answer", raw)
	60	+	if got != "short query" {
	61	+	t.Fatalf("ShortArgs = %q, want %q", got, "short query")
	62	+	}
	63	+	}