Self-review of PR #2949 surfaced two pre-existing defects that the
SSOT consolidation inherited from the original /notify handler. Both
are addressable in a small follow-up; shipping them as a separate PR
keeps the consolidation and the bug-fix individually reviewable.
Critical: byte-slice preview truncation produces invalid UTF-8
-------------------------------------------------------------
Pre-fix:
if len(preview) > 80 {
preview = preview[:80] + "…"
}
`len()` returns BYTES; `preview[:80]` slices on a byte boundary. For
agent-authored chat in CJK / emoji / accented characters, byte 80
lands mid-codepoint → invalid UTF-8 → Postgres JSONB rejects → INSERT
fails → activity_log row never written → message vanishes from chat
history on the next reload. The persistence-failure log fires but
operators have to grep to find it, and the user-visible regression
mode is identical to reno-stars.
Fix: extract `truncatePreviewRunes(s, maxRunes)` that walks the rune
boundary using `for i := range s` (Go's range over string yields rune
start indices). Cap at 80 RUNES not bytes — UI-friendly count, not
storage count.
Important: workspace-lookup error path swallows real DB errors
--------------------------------------------------------------
Pre-fix:
if err := w.db.QueryRowContext(...).Scan(&wsName); err != nil {
return ErrWorkspaceNotFound
}
Conflates `sql.ErrNoRows` (legit not-found → caller 404) with real
DB errors (connection drop, query timeout, pool exhaustion → caller
should 503). During a Postgres outage every notify call surfaced as
"workspace not found" — masking the actual incident in alerting and
making the symptom indistinguishable from "you typed a bad workspace
ID".
Fix: distinguish via `errors.Is(err, sql.ErrNoRows)` and wrap
non-not-found errors with `fmt.Errorf("agent_message: workspace
lookup: %w", err)`. Callers' existing fallback path (return 500 /
return error wrapped) handles the new shape correctly without any
changes — verified by running existing TestNotify_* and
TestMCPHandler_SendMessage_* tests.
Tests added (3 new, 11 total writer tests)
------------------------------------------
- TestTruncatePreviewRunes_RuneBoundary: 8-case table — ASCII, CJK,
exactly-at-max, emoji prefix. Asserts both correct visible output
AND `utf8.ValidString` on every result so the bug shape (invalid
UTF-8) can't recur.
- TestAgentMessageWriter_Send_NonASCIIMessagePersists: end-to-end
with a 200-rune CJK message (exceeds the 80-rune cap, would have
hit the byte-slice bug). Pins the INSERT summary contains valid
UTF-8 with exactly 80-rune body + ellipsis.
- TestAgentMessageWriter_Send_DBErrorOnLookupReturnsWrapped: pins the
DB-outage path returns a wrapped non-ErrWorkspaceNotFound error so
alerting can distinguish 404 from 503. Verified via mock
ExpectQuery returning a transient error.
Verified
--------
- `go vet ./internal/handlers/` clean
- `go build ./...` clean
- All 14 writer + caller tests pass (8 original + 3 new + AST gate +
TestNotify_* + TestMCPHandler_SendMessage_* sibling tests)
Per memory feedback_assert_exact_not_substring.md: every new test
asserts boundary behavior directly (UTF-8 validity, exact rune count,
errors.Is comparison) rather than substring-match in stringified
output.
Refs RFC #2945, PR #2949, PR #2944.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
1e01083e55