Optimize and simplify loops, table lookups, and branchless parsers

- Replace sequential colon-counting loop with branchless CTZ bitmask in src/pen.h
- Replace linear strchr with 256-bit ASCII punctuation bitmask in src/selection.c
- Flatten 3D color cube loop and precompute constants in src/palette.c
- Use static 256-byte LUT for hex decoding and bsearch for termcap in src/escape.c
- Replace capacity doubling while loops with branchless CLZ pow2 helpers across core
- Use direct memset/memcpy in src/snapshot.c
- Optimize input digit/byte formatting, alt-prefix path, and make keyboard state optional in src/input.c

2 files changed, 61 insertions, 0 deletions

diff --git a/tests/input_test.c b/tests/input_test.c
index 6ee2caa..1a44f42 100644
--- a/tests/input_test.c
+++ b/tests/input_test.c
@@ -101,9 +101,22 @@ int main(void)
     typed('b', TERM_MOD_ALT | TERM_MOD_CTRL); expect("\033\002");
     K(.key = TERM_KEY_BACKSPACE, .mods = TERM_MOD_ALT); expect("\033\177");
     K(.key = TERM_KEY_RETURN, .mods = TERM_MOD_ALT); expect("\033\r");
+    K(.key = TERM_KEY_TAB, .mods = TERM_MOD_ALT); expect("\033\t");
+    K(.key = TERM_KEY_TAB, .mods = TERM_MOD_ALT | TERM_MOD_SHIFT); expect("\033[Z");
+    K(.key = TERM_KEY_ESCAPE, .mods = TERM_MOD_ALT); expect("\033");
 
     K(.key = TERM_KEY_LEFT, .mods = TERM_MOD_ALT); expect("\033[1;3D");
 
+    {
+        char b_null[16];
+        struct term_input_result r = term_input_encode_key(
+            NULL,
+            &(struct term_key_event){ .key = TERM_KEY_UP, .action = TERM_KEY_PRESS },
+            &(struct term_modes){0},
+            b_null, sizeof(b_null));
+        assert(r.status == TERM_INPUT_BYTES && r.len == 3 && !memcmp(b_null, "\033[A", 3));
+    }
+
     K(.codepoint = 'b', .base = 'b', .text = 0x222B, .text_deferred = true);
     expect("");
 
diff --git a/tests/osc_test.c b/tests/osc_test.c
index ea0ef08..4d0e32b 100644
--- a/tests/osc_test.c
+++ b/tests/osc_test.c
@@ -387,6 +387,53 @@ static void test_osc_legacy_titles(void)
     term_free(t);
 }
 
+static void test_palette_and_theme(void)
+{
+    uint32_t c;
+    /* Hex formats */
+    assert(term_color_parse("#f00", &c) && c == 0xFFFF0000u);
+    assert(term_color_parse("#00ff00", &c) && c == 0xFF00FF00u);
+    assert(term_color_parse(" #0000ff \t", &c) && c == 0xFF0000FFu);
+    assert(term_color_parse("123456", &c) && c == 0xFF123456u);
+    assert(term_color_parse("abc", &c) && c == 0xFFAABBCCu);
+    assert(term_color_parse("#123456789abc", &c) && c == 0xFF12569au);
+
+    /* rgb: / rgbi: */
+    assert(term_color_parse("rgb:ff/80/00", &c) && c == 0xFFFF8000u);
+    assert(term_color_parse("rgbi:1.0/0.0/0.5", &c) && c == 0xFFFF0080u);
+    assert(term_color_parse("rgbi:.25/.5/.75", &c));
+
+    /* Errors */
+    assert(!term_color_parse(NULL, &c));
+    assert(!term_color_parse("#ff", &c));
+    assert(!term_color_parse("", &c));
+    assert(!term_color_parse("rgb:ff/80", &c));
+    assert(!term_color_parse("rgb:ff/80/00/11", &c));
+    assert(!term_color_parse("rgbi:2.0/0/0", &c));
+    assert(!term_color_parse("rgbi:./0/0", &c));
+
+    /* Theme APIs */
+    struct term_theme theme;
+    term_theme_default(&theme);
+    assert(term_theme_set_key(&theme, "foreground", "#112233") && theme.fg == 0xFF112233u);
+    assert(term_theme_set_key(&theme, "foreground", "") && theme.fg == 0xFFFFFFFFu);
+    assert(term_theme_set_key(&theme, "background", "#445566") && theme.bg == 0xFF445566u);
+    assert(term_theme_set_key(&theme, "background", "") && theme.bg == 0xFF1E1E2Eu);
+    assert(term_theme_set_key(&theme, "color0", "#010203") && theme.ansi[0] == 0xFF010203u);
+    assert(term_theme_set_key(&theme, "color15", "#fafbfc") && theme.ansi[15] == 0xFFFAFBFCu);
+    assert(term_theme_set_key(&theme, "color0", "") && theme.ansi[0] == 0xFF585B70u);
+    assert(!term_theme_set_key(&theme, "color16", "#000000"));
+    assert(!term_theme_set_key(&theme, "color01", "#000000"));
+    assert(!term_theme_set_key(&theme, "invalid", "#000000"));
+    assert(!term_theme_set_key(NULL, "foreground", "#000000"));
+    assert(!term_theme_set_key(&theme, NULL, "#000000"));
+    assert(!term_theme_set_key(&theme, "foreground", NULL));
+
+    struct term_theme hc;
+    term_theme_high_contrast(&hc);
+    assert(hc.bg == 0xFF000000u && hc.fg == 0xFFFFFFFFu);
+}
+
 int main(void)
 {
     test_osc52();
@@ -395,6 +442,7 @@ int main(void)
     test_osc_misc();
     test_osc_colors();
     test_osc_legacy_titles();
+    test_palette_and_theme();
     puts("PASS: OSC tests");
     return 0;
 }