feat: filter receive messages by conversation and query

docs/superpowers/plans/2026-07-09-stage-c-log-backed-receive-messages-loop.md

@@ -1573,19 +1573,19 @@ Implemented and verified in this loop:
 - Preserve current empty-source behavior and current `limit` behavior.
 - Do not add write/send/file-download behavior.
 
-- [ ] **Step 1: Write failing source/query test**
+- [x] **Step 1: Write failing source/query test**
 
 Extend `internal/isphere/source_test.go` with redacted fixtures proving `conversation_id` and keyword filtering.
 
-- [ ] **Step 2: Implement source query filtering**
+- [x] **Step 2: Implement source query filtering**
 
 Apply filters after decrypt/parse/normalize and before limit truncation, keeping deterministic source order.
 
-- [ ] **Step 3: Wire MCP args and verification**
+- [x] **Step 3: Wire MCP args and verification**
 
 Expose `conversation_id` and `query` on `isphere_receive_messages`, update tool tests and `verify-go-mcp.ps1` synthetic smoke.
 
-- [ ] **Step 4: Run full verification and commit**
+- [x] **Step 4: Run full verification and commit**
 
 Run:
 
@@ -1600,6 +1600,67 @@ Expected: all exit 0. Remove any generated root `isphere-mcp.exe` after build. C
 
 ---
 
+## Loop C18 Result
+
+Implemented and verified in this loop:
+
+- `isphere.ReceiveMessagesQuery` now supports `ConversationID` and `Query` in addition to `Limit`.
+- `EncryptedPacketLogSource.ReceiveMessages` filters normalized messages by exact conversation id and case-insensitive keyword match over message id, conversation id, sender id, receiver id, text, subject, and receipt id.
+- `isphere_receive_messages` MCP args now accept `conversation_id` and `query`, and pass them through to the source.
+- `scripts/verify-go-mcp.ps1` now calls configured file and directory source smokes with `conversation_id` plus keyword query arguments.
+- Existing empty-source and limit behavior remains unchanged.
+
+---
+
+## Loop C19: Receive-message `since` time filter slice
+
+**Goal:** Add the next safe receive-message filter from the core contract: `since`, using ISO-8601 input from the MCP caller and PacketReader epoch-millisecond timestamps from the normalized local readonly source.
+
+**Planned files:**
+- Modify: `internal/isphere/source.go`
+- Modify: `internal/isphere/source_test.go`
+- Modify: `internal/tools/isphere_read.go`
+- Modify: `internal/tools/isphere_read_test.go`
+- Modify: `scripts/verify-go-mcp.ps1`
+- Modify: `docs/go-mcp-runbook.md`
+- Modify: `docs/current-status-card.md`
+- Modify: `docs/superpowers/plans/2026-07-09-stage-c-log-backed-receive-messages-loop.md`
+
+**Planned behavior:**
+- Add `Since` to `ReceiveMessagesQuery` and `ReceiveMessagesArgs`.
+- Accept RFC3339/ISO-8601 input for `since`.
+- Compare against message `Timestamp` when it is an epoch-millisecond value.
+- Return a clear error for invalid `since` input rather than silently ignoring it.
+- Keep `cursor`, `source_preference`, and broader pagination deferred.
+- Do not add write/send/file-download behavior.
+
+- [ ] **Step 1: Write failing source `since` test**
+
+Use synthetic PacketReader fixtures before and after an RFC3339 threshold.
+
+- [ ] **Step 2: Implement source `since` filtering**
+
+Parse `since` once per receive call and filter normalized messages by timestamp.
+
+- [ ] **Step 3: Wire MCP args and verification**
+
+Expose `since` on `isphere_receive_messages`, update tool tests and `verify-go-mcp.ps1` synthetic smoke.
+
+- [ ] **Step 4: Run full verification and commit**
+
+Run:
+
+```powershell
+git diff --check
+go test ./...
+go build ./cmd/isphere-mcp
+powershell -NoProfile -ExecutionPolicy Bypass -File scripts/verify-go-mcp.ps1
+```
+
+Expected: all exit 0. Remove any generated root `isphere-mcp.exe` after build. Commit exact C19 paths only and rewrite the next loop from actual results.
+
+---
+
 ## Self-Review
 
 - Spec coverage: the plan follows the user's cyclic requirement: plan first, implement one loop at a time, update the next loop after each result, and ask only on blockers.