diff --git a/hive-agent/src/stream_enrich.rs b/hive-agent/src/stream_enrich.rs
index 39921b9d..654ac714 100644
--- a/hive-agent/src/stream_enrich.rs
+++ b/hive-agent/src/stream_enrich.rs
@@ -1048,3 +1048,381 @@ fn trim_str(s: &str, max: usize) -> String {
 fn json_str(s: &str) -> String {
     serde_json::to_string(s).unwrap_or_else(|_| s.to_owned())
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn one(v: &Value) -> TermMsg {
+        let mut ctx = ClassifyCtx::default();
+        let rows = classify_stream_value(v, &mut ctx);
+        assert_eq!(rows.len(), 1, "expected exactly one row for {v}");
+        rows.into_iter().next().unwrap()
+    }
+
+    // -----------------------------------------------------------------
+    // dispatch
+    // -----------------------------------------------------------------
+
+    #[test]
+    fn terminal_event_types_render_nothing() {
+        for t in ["result", "rate_limit_event"] {
+            let mut ctx = ClassifyCtx::default();
+            assert!(
+                classify_stream_value(&json!({ "type": t }), &mut ctx).is_empty(),
+                "{t} should be dropped"
+            );
+        }
+    }
+
+    /// The catch-all exists so a claude event shape nobody anticipated stays
+    /// *visible* rather than vanishing. Losing it is silent, which is why it
+    /// gets a test rather than a comment.
+    #[test]
+    fn unrecognised_shape_falls_through_loudly() {
+        let m = one(&json!({ "type": "something_new", "detail": "x" }));
+        assert_eq!(m.level, Level::Warn);
+        assert_eq!(m.icon.as_deref(), Some("!"));
+        assert!(m.summary.contains("something_new"));
+    }
+
+    #[test]
+    fn catch_all_truncates_a_huge_payload() {
+        let m = one(&json!({ "type": "unknown", "blob": "x".repeat(5_000) }));
+        assert_eq!(m.summary.chars().count(), 201, "200 chars plus the ellipsis");
+        assert!(m.summary.ends_with('…'));
+    }
+
+    /// Task events are matched on `subtype` *regardless of `type`* — a
+    /// deliberate asymmetry with every other arm, and one a refactor that
+    /// "tidies" the dispatch into a single match on `type` would silently
+    /// break.
+    #[test]
+    fn task_events_dispatch_on_subtype_not_type() {
+        let m = one(&json!({
+            "type": "assistant",
+            "subtype": "task_started",
+            "task_id": "abcdef1234567890",
+            "description": "do a thing",
+        }));
+        assert!(m.summary.starts_with("task abcdef12 started"), "{}", m.summary);
+        assert!(
+            !m.summary.contains("1234567890"),
+            "task id is truncated to 8 chars"
+        );
+    }
+
+    #[test]
+    fn a_failed_task_notification_is_an_error_row() {
+        let m = one(&json!({
+            "type": "x", "subtype": "task_notification",
+            "task_id": "t1", "status": "failed",
+        }));
+        assert_eq!(m.level, Level::Error);
+    }
+
+    // -----------------------------------------------------------------
+    // system events
+    // -----------------------------------------------------------------
+
+    #[test]
+    fn startup_noise_is_dropped_but_an_unknown_subtype_is_not() {
+        let mut ctx = ClassifyCtx::default();
+        assert!(
+            classify_stream_value(&json!({ "type": "system", "subtype": "init" }), &mut ctx)
+                .is_empty()
+        );
+        // The pairing is the point: "init produces nothing" only means
+        // something if a *different* subtype produces something.
+        let m = one(&json!({ "type": "system", "subtype": "brand_new" }));
+        assert_eq!(m.summary, "⚙ brand_new");
+    }
+
+    #[test]
+    fn system_severity_is_carried_by_subtype() {
+        let cases = [
+            ("api_error", Level::Error),
+            ("api_retry", Level::Warn),
+            ("status", Level::Debug),
+        ];
+        for (subtype, want) in cases {
+            let m = one(&json!({ "type": "system", "subtype": subtype }));
+            assert_eq!(m.level, want, "{subtype}");
+        }
+    }
+
+    /// Coalescing is what stops a heartbeat from flooding the terminal: rows
+    /// sharing a key collapse into one. A missing key is invisible in every
+    /// unit except the rendered stream.
+    #[test]
+    fn repeating_rows_carry_a_coalesce_key() {
+        let tick = one(&json!({ "type": "system", "subtype": "status" }));
+        assert_eq!(tick.coalesce_key.as_deref(), Some("status-tick"));
+
+        let think = one(&json!({
+            "type": "system", "subtype": "thinking_tokens", "estimated_tokens": 1234,
+        }));
+        assert_eq!(think.coalesce_key.as_deref(), Some("thinking-tok"));
+        assert_eq!(think.summary, "thinking… ~1234 tokens");
+
+        // Same subtype, no count: still coalesces, still says something.
+        let bare = one(&json!({ "type": "system", "subtype": "thinking_tokens" }));
+        assert_eq!(bare.summary, "thinking…");
+        assert_eq!(bare.coalesce_key.as_deref(), Some("thinking-tok"));
+    }
+
+    #[test]
+    fn commands_changed_expands_into_the_command_list() {
+        let m = one(&json!({
+            "type": "system", "subtype": "commands_changed",
+            "commands": [{ "name": "compact" }, { "name": "loop" }],
+        }));
+        assert_eq!(m.summary, "⚙ commands changed · 2 available");
+        assert_eq!(m.body.as_deref(), Some("/compact\n/loop"));
+    }
+
+    #[test]
+    fn api_retry_summarises_every_field_it_was_given() {
+        let m = one(&json!({
+            "type": "system", "subtype": "api_retry",
+            "attempt": 2, "max_retries": 5,
+            "error_status": 529, "retry_delay_ms": 1500.4,
+        }));
+        assert_eq!(m.summary, "⚠ api retry · 2/5 · HTTP 529 · 1500ms");
+    }
+
+    /// `error` wins over `error_status` — the operator gets the message, not
+    /// the number, whenever there is one.
+    #[test]
+    fn api_error_prefers_the_message_over_the_status() {
+        let with_msg = one(&json!({
+            "type": "system", "subtype": "api_error",
+            "error": "overloaded", "error_status": 529,
+        }));
+        assert_eq!(with_msg.summary, "✗ api error · overloaded");
+
+        let status_only =
+            one(&json!({ "type": "system", "subtype": "api_error", "error_status": 529 }));
+        assert_eq!(status_only.summary, "✗ api error · HTTP 529");
+
+        let neither = one(&json!({ "type": "system", "subtype": "api_error" }));
+        assert_eq!(neither.summary, "✗ api error · unknown");
+    }
+
+    // -----------------------------------------------------------------
+    // tool results
+    // -----------------------------------------------------------------
+
+    /// The 120-char boundary decides between an inline summary and an
+    /// expandable body, and it counts *characters*, so a multi-byte result is
+    /// the case that would break a byte-based rewrite.
+    #[test]
+    fn tool_result_summary_boundary_counts_characters() {
+        let at = "a".repeat(120);
+        assert_eq!(summarize_tool_result(&at, &at), at);
+
+        let over = "a".repeat(121);
+        let s = summarize_tool_result(&over, &over);
+        assert!(s.starts_with("1L · "), "{s}");
+        assert!(s.ends_with('…'));
+
+        // 120 non-ASCII chars is 240 bytes: byte-length would call this long.
+        let wide = "é".repeat(120);
+        assert_eq!(summarize_tool_result(&wide, &wide), wide);
+    }
+
+    #[test]
+    fn an_empty_tool_result_says_so() {
+        assert_eq!(summarize_tool_result("", ""), "(empty)");
+        assert_eq!(summarize_tool_result("  \n\t ", ""), "(empty)");
+    }
+
+    #[test]
+    fn a_long_tool_result_reports_its_line_count() {
+        let txt = (0..40).map(|i| format!("line {i}\n")).collect::<String>();
+        let trimmed: String = txt.split_whitespace().collect::<Vec<_>>().join(" ");
+        assert!(summarize_tool_result(&txt, &trimmed).starts_with("40L · "));
+    }
+
+    /// Only a *matched* pair is claude's wrapper. A result that merely starts
+    /// with the opening tag is real output and must survive intact.
+    #[test]
+    fn the_error_wrapper_is_stripped_only_when_balanced() {
+        assert_eq!(
+            strip_tool_use_error_wrapper("<tool_use_error>boom</tool_use_error>"),
+            "boom"
+        );
+        assert_eq!(
+            strip_tool_use_error_wrapper("  <tool_use_error> boom </tool_use_error>  "),
+            "boom"
+        );
+        let unbalanced = "<tool_use_error>boom";
+        assert_eq!(strip_tool_use_error_wrapper(unbalanced), unbalanced);
+        assert_eq!(strip_tool_use_error_wrapper("plain"), "plain");
+    }
+
+    fn tool_result(text: &str, is_error: bool, id: &str) -> Value {
+        json!({
+            "type": "user",
+            "message": { "content": [{
+                "type": "tool_result",
+                "tool_use_id": id,
+                "is_error": is_error,
+                "content": [{ "type": "text", "text": text }],
+            }]},
+        })
+    }
+
+    #[test]
+    fn a_short_result_gets_an_icon_and_a_long_one_gets_a_body() {
+        let short = one(&tool_result("ok", false, "t1"));
+        assert_eq!(short.icon.as_deref(), Some("←"));
+        assert!(short.body.is_none(), "short results are not expandable");
+
+        let long = one(&tool_result(&"x".repeat(500), false, "t1"));
+        assert!(long.icon.is_none());
+        assert_eq!(long.body.as_deref().map(str::len), Some(500));
+    }
+
+    #[test]
+    fn an_error_result_is_an_error_row_with_the_wrapper_gone() {
+        let m = one(&tool_result(
+            "<tool_use_error>file not found</tool_use_error>",
+            true,
+            "t1",
+        ));
+        assert_eq!(m.level, Level::Error);
+        assert_eq!(m.icon.as_deref(), Some("✗"));
+        assert_eq!(m.summary, "file not found");
+    }
+
+    /// The one piece of *cross-event* state in this module: the tool name is
+    /// learned from the assistant event and read back on the user event that
+    /// answers it. Nothing but a test spanning both events can catch it
+    /// breaking — and when it does, an inbox message silently renders as
+    /// plain text instead of markdown.
+    #[test]
+    fn a_recv_result_is_markdown_only_because_the_tool_use_was_seen_first() {
+        let mut ctx = ClassifyCtx::default();
+        let body = "**bold** message from a peer";
+
+        // Without the correlation, it is an ordinary result.
+        let cold = classify_stream_value(&tool_result(body, false, "call-1"), &mut ctx);
+        assert_eq!(cold[0].body_format, None);
+        assert!(!cold[0].summary.starts_with("recv ←"));
+
+        // Feed the assistant event that names the tool, then the same result.
+        classify_stream_value(
+            &json!({
+                "type": "assistant",
+                "message": { "content": [{
+                    "type": "tool_use", "id": "call-1",
+                    "name": "mcp__hyperhive__recv", "input": {},
+                }]},
+            }),
+            &mut ctx,
+        );
+        let warm = classify_stream_value(&tool_result(body, false, "call-1"), &mut ctx);
+        assert!(warm[0].summary.starts_with("recv ← "), "{}", warm[0].summary);
+        assert_eq!(warm[0].body_format, Some(BodyFormat::Markdown));
+        assert_eq!(warm[0].body.as_deref(), Some(body));
+    }
+
+    #[test]
+    fn a_recv_result_with_no_content_stays_an_ordinary_row() {
+        let mut ctx = ClassifyCtx::default();
+        ctx.record_tool_use("call-1", "mcp__hyperhive__recv");
+        let m = one_with(&tool_result("   ", false, "call-1"), &mut ctx);
+        assert!(!m.summary.starts_with("recv ←"));
+        assert_eq!(m.summary, "(empty)");
+    }
+
+    fn one_with(v: &Value, ctx: &mut ClassifyCtx) -> TermMsg {
+        let rows = classify_stream_value(v, ctx);
+        assert_eq!(rows.len(), 1, "expected exactly one row for {v}");
+        rows.into_iter().next().unwrap()
+    }
+
+    // -----------------------------------------------------------------
+    // assistant content
+    // -----------------------------------------------------------------
+
+    #[test]
+    fn assistant_text_becomes_a_markdown_body_with_no_summary() {
+        let m = one(&json!({
+            "type": "assistant",
+            "message": { "content": [{ "type": "text", "text": "# hi" }]},
+        }));
+        assert_eq!(m.summary, "");
+        assert_eq!(m.body.as_deref(), Some("# hi"));
+        assert_eq!(m.body_format, Some(BodyFormat::Markdown));
+    }
+
+    #[test]
+    fn blank_assistant_text_produces_no_row_at_all() {
+        let mut ctx = ClassifyCtx::default();
+        let rows = classify_stream_value(
+            &json!({
+                "type": "assistant",
+                "message": { "content": [{ "type": "text", "text": "   \n " }]},
+            }),
+            &mut ctx,
+        );
+        assert!(rows.is_empty());
+    }
+
+    #[test]
+    fn one_assistant_event_can_produce_several_rows() {
+        let mut ctx = ClassifyCtx::default();
+        let rows = classify_stream_value(
+            &json!({
+                "type": "assistant",
+                "message": { "content": [
+                    { "type": "text", "text": "doing it" },
+                    { "type": "thinking", "thinking": "hmm" },
+                    { "type": "tool_use", "id": "t1", "name": "Bash",
+                      "input": { "command": "ls" } },
+                    { "type": "something_else" },
+                ]},
+            }),
+            &mut ctx,
+        );
+        assert_eq!(rows.len(), 3, "the unknown content block is skipped");
+        assert_eq!(rows[1].icon.as_deref(), Some("💭"));
+        // The tool_use was recorded for later correlation as a side effect.
+        assert_eq!(ctx.tool_name("t1"), Some("Bash"));
+    }
+
+    // -----------------------------------------------------------------
+    // string helpers
+    // -----------------------------------------------------------------
+
+    #[test]
+    fn token_counts_shorten_at_each_threshold() {
+        assert_eq!(fmt_tok(0), "0");
+        assert_eq!(fmt_tok(999), "999");
+        assert_eq!(fmt_tok(1_000), "1k");
+        assert_eq!(fmt_tok(999_999), "999k");
+        assert_eq!(fmt_tok(1_000_000), "1.0M");
+        assert_eq!(fmt_tok(1_250_000), "1.2M");
+    }
+
+    #[test]
+    fn trim_str_collapses_whitespace_and_counts_characters() {
+        assert_eq!(trim_str("a  b\n\tc", 99), "a b c");
+        assert_eq!(trim_str("abcdef", 3), "abc…");
+        // Exactly at the limit: no ellipsis.
+        assert_eq!(trim_str("abc", 3), "abc");
+        // 4 chars / 8 bytes — a byte-based limit would cut this at 2.
+        assert_eq!(trim_str("éééé", 4), "éééé");
+    }
+
+    #[test]
+    fn matrix_ids_shorten_to_something_recognisable() {
+        assert_eq!(fmt_user("@mara:pr1ma.darkest.space"), "@mara");
+        assert_eq!(fmt_user("@mara"), "@mara");
+        assert_eq!(fmt_room("#hive-chat:pr1ma.darkest.space"), "#hive-chat");
+        assert_eq!(fmt_room("!abcdefghijkl:server"), "!abcdefgh");
+        assert_eq!(fmt_room("plain name"), "plain name");
+    }
+}