fleetd #782: tell a placeholder hint apart from real typed text in the prompt box

PromptBox probed the detection region, which carries no ANSI styling, so a dim
placeholder hint (the pane's last submitted prompt) read as the operator's draft
and held the delivery forever.

Move the probe to the visible region, read with strip_ansi:false
(AgentControl.readWithStyling), skip leading SGR escapes before matching the
box marker, use Character.isSpaceChar so a non-breaking space in an empty box
counts as padding, and exclude any character drawn inside a faint (SGR 2) span
from the box content. An all-faint box now classifies as EMPTY instead of
UNREADABLE.

fleetd/src/main/java/dev/ltms/fleet/herdr/AgentControl.java

@@ -137,6 +137,18 @@ public final class AgentControl {
         return result.path("read").path("text").asText("");
     }
 
+    /**
+     * Read an agent's terminal with its ANSI styling kept, instead of the stripped text {@link
+     * #read} returns. Needed when a caller must tell apart text the pane draws dim (a placeholder
+     * hint) from text drawn plain (the operator's own typing).
+     *
+     * @param source one of {@code visible|recent|recent_unwrapped|detection}
+     */
+    public String readWithStyling(String target, String source) {
+        JsonNode result = agentCall("agent.read", target, Map.of("source", source, "strip_ansi", false));
+        return result.path("read").path("text").asText("");
+    }
+
     /** Current agent record (status, session UUID, pane). */
     public Agent get(String target) {
         return Agent.from(agentCall("agent.get", target, Map.of()).get("agent"));

fleetd/src/main/java/dev/ltms/fleet/herdr/PromptBox.java

@@ -3,9 +3,12 @@ package dev.ltms.fleet.herdr;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
 
 /**
  * Whether an agent pane's input box is clear for a delivery.
@@ -29,20 +32,22 @@ public final class PromptBox {
     private static final Logger log = LoggerFactory.getLogger(PromptBox.class);
 
     /**
-     * herdr {@code agent.read} source. {@code detection} is the region herdr itself uses for status
-     * detection, so the input box is always drawn in it. It is not a short tail: it carries transcript
-     * scrollback above the box, including earlier prompts the operator has already submitted, which is
-     * why only the last box line on it is the live one.
+     * herdr {@code agent.read} source, read with its ANSI styling kept. The input box is always
+     * drawn here, carrying transcript scrollback above it, which is why only the last box line is
+     * the live one. Styling must survive the read because the pane draws a placeholder hint — the
+     * pane's own last submitted prompt — in the same spot as unsubmitted text, dimmed; only the
+     * escape codes tell the two apart.
      */
-    static final String PROBE_SOURCE = "detection";
+    static final String PROBE_SOURCE = "visible";
 
     /** Consecutive holds for one target before one warning is logged. */
     static final int HOLD_WARN_STREAK = 20;
 
     /**
-     * Input box markers, each matched only as a line's first characters: the caret the current TUI
-     * draws, and the bordered box an older one drew. A marker further along a line is transcript text,
-     * such as a caret inside something the operator quoted.
+     * Input box markers, each matched only as a line's first characters once any leading ANSI
+     * escape codes are skipped: the caret the current TUI draws, and the bordered box an older one
+     * drew. A marker further along a line is transcript text, such as a caret inside something the
+     * operator quoted.
      */
     private static final List<String> BOX_MARKERS = List.of("❯", "│ >");
 
@@ -52,6 +57,15 @@ public final class PromptBox {
     /** Block glyphs a terminal capture can leave in an otherwise empty box for the cursor cell. */
     private static final String CURSOR_GLYPHS = "█▉▊▋▌▍▎▏";
 
+    /** An SGR escape sequence, e.g. {@code ESC[2m} (faint) or {@code ESC[0m} (reset). */
+    private static final Pattern SGR = Pattern.compile("\u001b\\[([0-9;]*)m");
+
+    /** The SGR code that dims text — herdr's placeholder hint is drawn inside a span of this. */
+    private static final String FAINT_CODE = "2";
+
+    /** The SGR code (or an empty code list) that clears every attribute, including faint. */
+    private static final List<String> RESET_CODES = List.of("", "0");
+
     /** What a box holds: nothing, unsubmitted characters, or a pane this cannot read as a box. */
     public enum State { EMPTY, DRAFT, UNREADABLE }
 
@@ -94,7 +108,7 @@ public final class PromptBox {
     private Reading inspect(String target) {
         String pane;
         try {
-            pane = agents.read(target, PROBE_SOURCE);
+            pane = agents.readWithStyling(target, PROBE_SOURCE);
         } catch (RuntimeException e) {
             log.debug("prompt box read for {} failed, holding delivery: {}", target, e.getMessage());
             return new Reading(State.UNREADABLE, 0);
@@ -114,10 +128,9 @@ public final class PromptBox {
      * an earlier turn's marker survives; treating that as a live turn would make {@link State#EMPTY}
      * unreachable and hold every delivery forever.
      *
-     * <p>Whitespace, a trailing box border and a cursor block count as nothing. Any other character
-     * counts as the operator's unsubmitted text, including a placeholder hint a future TUI might draw
-     * there; that direction holds a delivery it could have sent, which {@link #HOLD_WARN_STREAK} makes
-     * visible.
+     * <p>Whitespace, a trailing box border and a cursor block count as nothing. A placeholder hint —
+     * text the pane draws faint, in the same spot as unsubmitted text — also counts as nothing: only
+     * a character drawn outside a faint span is the operator's own typing.
      */
     static Reading classify(String pane) {
         if (pane == null || pane.isBlank()) return new Reading(State.UNREADABLE, 0);
@@ -142,28 +155,77 @@ public final class PromptBox {
         return found;
     }
 
-    /** Length of the box marker this line starts with, or {@code 0} if it starts with none. */
+    /**
+     * Length of the marker prefix — any leading SGR escape codes, then a box marker — this line
+     * starts with, or {@code 0} if it starts with neither. The colour drawn on the caret itself
+     * (e.g. an empty box's grey) sits before the marker glyph, so it must be skipped before the
+     * marker can match.
+     */
     private static int markerLength(String line) {
+        int skip = leadingEscapeLength(line);
         for (String marker : BOX_MARKERS) {
-            if (line.startsWith(marker)) return marker.length();
+            if (line.startsWith(marker, skip)) return skip + marker.length();
         }
         return 0;
     }
 
+    /** Length of the run of SGR escape codes starting at the beginning of {@code line}. */
+    private static int leadingEscapeLength(String line) {
+        Matcher m = SGR.matcher(line);
+        int pos = 0;
+        while (m.find(pos) && m.start() == pos) pos = m.end();
+        return pos;
+    }
+
     private static String firstLine(String text) {
         int newline = text.indexOf('\n');
         return newline < 0 ? text : text.substring(0, newline);
     }
 
-    /** The text the box holds: its own line after the marker, stripped of border, padding and cursor. */
+    /** One rendered character of a box line, and whether it was drawn inside a faint (dim) span. */
+    private record Glyph(char c, boolean faint) {
+    }
+
+    /**
+     * The text the box holds: its own line after the marker, with border, padding, cursor and any
+     * faint (placeholder-hint) text left out — only a character drawn outside a faint span is the
+     * operator's own typing.
+     */
     private static String boxContent(String boxLine) {
-        String line = boxLine.substring(markerLength(boxLine)).stripTrailing();
-        if (line.endsWith("│")) line = line.substring(0, line.length() - 1);
+        List<Glyph> glyphs = renderedGlyphs(boxLine.substring(markerLength(boxLine)));
+        int end = glyphs.size();
+        while (end > 0 && isBoxPadding(glyphs.get(end - 1).c())) end--;
+        if (end > 0 && glyphs.get(end - 1).c() == '│') end--;
         StringBuilder content = new StringBuilder();
-        for (char c : line.toCharArray()) {
-            if (Character.isWhitespace(c) || CURSOR_GLYPHS.indexOf(c) >= 0) continue;
-            content.append(c);
+        for (int i = 0; i < end; i++) {
+            Glyph glyph = glyphs.get(i);
+            if (glyph.faint() || isBoxPadding(glyph.c())) continue;
+            content.append(glyph.c());
         }
         return content.toString();
     }
+
+    /** Decode {@code text} into its rendered characters, tracking the faint (SGR 2) span each sits in. */
+    private static List<Glyph> renderedGlyphs(String text) {
+        List<Glyph> glyphs = new ArrayList<>();
+        Matcher m = SGR.matcher(text);
+        boolean faint = false;
+        int i = 0;
+        while (i < text.length()) {
+            if (m.find(i) && m.start() == i) {
+                String codes = m.group(1);
+                if (RESET_CODES.contains(codes)) faint = false;
+                else if (FAINT_CODE.equals(codes)) faint = true;
+                i = m.end();
+                continue;
+            }
+            glyphs.add(new Glyph(text.charAt(i), faint));
+            i++;
+        }
+        return glyphs;
+    }
+
+    private static boolean isBoxPadding(char c) {
+        return Character.isWhitespace(c) || Character.isSpaceChar(c) || CURSOR_GLYPHS.indexOf(c) >= 0;
+    }
 }

fleetd/src/test/java/dev/ltms/fleet/herdr/FakeHerdr.java

@@ -254,10 +254,11 @@ public final class FakeHerdr implements HerdrClient {
     }
 
     /**
-     * Override the text {@code agent.read} returns for the {@code detection} source only — the
-     * prompt/footer tail herdr uses for status detection, a different region from the transcript the
-     * other sources carry. Needed by a test whose subject reads the input box, since one
-     * {@link #readText} cannot be both a worker's transcript and a lead's empty prompt.
+     * Override the text {@code agent.read} returns for the {@code detection} and {@code visible}
+     * sources only — the prompt/footer tail herdr uses for status detection and input-box probing, a
+     * different region from the transcript the other sources carry. Needed by a test whose subject
+     * reads the input box, since one {@link #readText} cannot be both a worker's transcript and a
+     * lead's empty prompt.
      */
     public FakeHerdr detectionText(String text) {
         this.detectionText = text;
@@ -413,8 +414,8 @@ public final class FakeHerdr implements HerdrClient {
                 }
                 case "agent.read" -> {
                     Object source = params instanceof Map<?, ?> m ? m.get("source") : null;
-                    String text = "detection".equals(source) && detectionText != null
-                            ? detectionText : readText;
+                    boolean probeSource = "detection".equals(source) || "visible".equals(source);
+                    String text = probeSource && detectionText != null ? detectionText : readText;
                     yield mapper.readTree(mapper.writeValueAsString(
                             java.util.Map.of("type", "agent_read", "read", java.util.Map.of("text", text))));
                 }

fleetd/src/test/java/dev/ltms/fleet/herdr/PromptBoxTest.java

@@ -12,6 +12,18 @@ class PromptBoxTest {
     private static final String EMPTY = FakeHerdr.IDLE_PROMPT_CARET;
     private static final String DRAFTED = FakeHerdr.DRAFTED_PROMPT_CARET;
 
+    /** An empty box: the pane draws a placeholder hint (its last submitted prompt) at the caret, faint. */
+    private static final String HINT_1 = "❯\u00a0\u001b[0m\u001b[2mstart md2trilium work for #2\u001b[0m";
+
+    /** Same shape as {@link #HINT_1}, a different placeholder hint. */
+    private static final String HINT_2 = "❯\u00a0\u001b[0m\u001b[2myes, push them\u001b[0m";
+
+    /** An empty box with no hint: the caret itself is drawn grey, with escape codes before the marker. */
+    private static final String EMPTY_GREY_CARET = "\u001b[0m\u001b[38;2;153;153;153m❯\u00a0\u001b[0m";
+
+    /** An empty box with no styling at all. */
+    private static final String EMPTY_PLAIN = "❯\u00a0";
+
     // --- pure classification -------------------------------------------------
 
     @Test
@@ -57,7 +69,7 @@ class PromptBoxTest {
     void theLastBoxLineOnThePaneIsTheLiveOne() {
         assertEquals(PromptBox.State.DRAFT,
                 PromptBox.classify("❯ an earlier prompt\n⏺ its answer\n❯ typing now").state(),
-                "the detection region carries scrollback, so earlier prompts sit above the live box");
+                "the probed region carries scrollback, so earlier prompts sit above the live box");
         assertEquals(PromptBox.State.EMPTY,
                 PromptBox.classify("❯ an earlier prompt\n⏺ its answer\n❯").state());
     }
@@ -90,18 +102,54 @@ class PromptBoxTest {
                 "that marker survives in scrollback, and holding on it would hold every delivery forever");
     }
 
+    @Test
+    void aPlaceholderHintReadsAsAnEmptyBox() {
+        assertEquals(new PromptBox.Reading(PromptBox.State.EMPTY, 0), PromptBox.classify(HINT_1),
+                "the hint is the pane's own last prompt, drawn faint — it is not the operator's typing");
+        assertEquals(new PromptBox.Reading(PromptBox.State.EMPTY, 0), PromptBox.classify(HINT_2));
+    }
+
+    @Test
+    void anEmptyBoxWithAGreyCaretReadsAsEmpty() {
+        assertEquals(new PromptBox.Reading(PromptBox.State.EMPTY, 0), PromptBox.classify(EMPTY_GREY_CARET),
+                "the caret's own colour sits before the marker and must not stop the marker matching");
+    }
+
+    @Test
+    void anEmptyBoxWithNoStylingAtAllReadsAsEmpty() {
+        assertEquals(new PromptBox.Reading(PromptBox.State.EMPTY, 0), PromptBox.classify(EMPTY_PLAIN));
+    }
+
+    @Test
+    void typedTextWithNoStylingIsADraftAndCountsItsCharacters() {
+        PromptBox.Reading reading = PromptBox.classify("❯\u00a0deploy the thing");
+        assertEquals(PromptBox.State.DRAFT, reading.state());
+        assertEquals("deploythething".length(), reading.characters());
+    }
+
+    @Test
+    void typedTextAfterAFaintHintCountsOnlyTheTextOutsideTheFaintSpan() {
+        PromptBox.Reading reading =
+                PromptBox.classify("❯\u00a0\u001b[0m\u001b[2mhint\u001b[0m and typed");
+        assertEquals(PromptBox.State.DRAFT, reading.state());
+        assertEquals("andtyped".length(), reading.characters(),
+                "the faint hint is excluded; only \"and typed\" was drawn plain");
+    }
+
     // --- the gate ------------------------------------------------------------
 
     @Test
-    void anEmptyBoxClearsTheGateAndReadsTheDetectionRegion() {
+    void anEmptyBoxClearsTheGateAndReadsTheVisibleRegionWithStylingKept() {
         FakeHerdr herdr = new FakeHerdr().detectionText(EMPTY);
 
         assertTrue(new PromptBox(new AgentControl(herdr)).clearToSubmit("term_a"));
 
         @SuppressWarnings("unchecked")
         var params = (java.util.Map<String, Object>) herdr.lastCall("agent.read").params();
-        assertEquals("detection", params.get("source"),
-                "the input box is drawn in the detection region, not in transcript scrollback");
+        assertEquals("visible", params.get("source"),
+                "the input box is drawn in the visible region, not in transcript scrollback");
+        assertEquals(false, params.get("strip_ansi"),
+                "styling must survive the read, or a faint placeholder hint reads as plain typed text");
     }
 
     @Test