feat: load packet logs from configured source

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

@@ -795,7 +795,7 @@ Implemented and verified in this loop:
 - Configured behavior: env var set to a local text file means the server reads non-empty encrypted Base64 lines from that file into `isphere.EncryptedPacketLogSource{Lines: lines}`.
 - Evidence rule: the configured file should live under ignored `runs/` or another operator-local path; the loader must not require or commit raw evidence.
 
-- [ ] **Step 1: Write failing file loader test**
+- [x] **Step 1: Write failing file loader test**
 
 Create `internal/isphere/file_source_test.go` first and run:
 
@@ -805,23 +805,23 @@ go test ./internal/isphere -run TestLoadEncryptedPacketLogSourceFromFileReadsNon
 
 Expected initial failure: loader function/type does not exist.
 
-- [ ] **Step 2: Implement file loader**
+- [x] **Step 2: Implement file loader**
 
 Implement a small loader that reads a UTF-8 text file, trims whitespace, skips blank lines, and returns `EncryptedPacketLogSource{Lines: lines}`. It should return clear path/context errors for missing or unreadable files.
 
-- [ ] **Step 3: Write failing env-wired server test**
+- [x] **Step 3: Write failing env-wired server test**
 
 Update `internal/mcpserver/server_test.go` with a temp encrypted fixture file and a test that sets `ISPHERE_PACKET_LOG_FILE`, constructs the env-wired server, calls `isphere_receive_messages`, and expects one redacted message. Run the specific test before implementation.
 
-- [ ] **Step 4: Implement env-wired server construction**
+- [x] **Step 4: Implement env-wired server construction**
 
 Add `NewServerFromEnv()` or equivalent env-aware construction. Keep `NewServer()` as the empty default for existing tests. Update `cmd/isphere-mcp/main.go` to use the env-aware server.
 
-- [ ] **Step 5: Update operator verification/docs**
+- [x] **Step 5: Update operator verification/docs**
 
 Extend `scripts/verify-go-mcp.ps1` so default verification still asserts zero messages when no env var is set. Document optional `ISPHERE_PACKET_LOG_FILE` usage in `docs/go-mcp-runbook.md` and update the status card.
 
-- [ ] **Step 6: Run full verification and commit**
+- [x] **Step 6: Run full verification and commit**
 
 Run:
 
@@ -836,6 +836,67 @@ Expected: all exit 0. Remove any generated root `isphere-mcp.exe` after build. C
 
 ---
 
+## Loop C5 Result
+
+Implemented and verified in this loop:
+
+- `internal/isphere.LoadEncryptedPacketLogSourceFromFile(path)` reads non-empty encrypted Base64 PacketReader log lines from an operator-local text file and returns `EncryptedPacketLogSource{Lines: lines}`.
+- `internal/mcpserver.NewServerFromEnv()` reads `ISPHERE_PACKET_LOG_FILE` when set, otherwise preserves the empty default receive source.
+- `cmd/isphere-mcp/main.go` now uses the env-aware server constructor and fails fast on invalid configuration.
+- `scripts/verify-go-mcp.ps1` now exercises `NewServerFromEnv()` with `ISPHERE_PACKET_LOG_FILE` cleared and confirms the deterministic empty-source behavior.
+- Docs now explain optional `ISPHERE_PACKET_LOG_FILE` usage and reinforce that raw evidence must remain under ignored/operator-local paths.
+- Verification completed for C5 with `git diff --check`, `go test ./...`, `go build ./cmd/isphere-mcp`, and `powershell -NoProfile -ExecutionPolicy Bypass -File scripts/verify-go-mcp.ps1`; the generated root `isphere-mcp.exe` build artifact was removed.
+
+---
+
+## Loop C6: Fixture-backed operator smoke for configured receive source
+
+**Goal:** Extend repeatable operator verification so a synthetic encrypted PacketReader fixture file proves `ISPHERE_PACKET_LOG_FILE` can drive `isphere_receive_messages` end-to-end without committing raw evidence.
+
+**Planned files:**
+- 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:**
+- Existing default smoke remains: unset `ISPHERE_PACKET_LOG_FILE` returns `messages: []`.
+- New fixture smoke creates a temporary synthetic/redacted PacketReader plaintext, encrypts it with the known log policy inside the temporary Go harness, writes one encrypted line to a temp file, sets `ISPHERE_PACKET_LOG_FILE` to that temp file, starts `mcpserver.NewServerFromEnv()`, calls `isphere_receive_messages`, and asserts one normalized message.
+- No raw N12-pre evidence or decrypted user content is written to the repo.
+
+- [ ] **Step 1: Capture current fixture-smoke gap**
+
+Run the current verification script and note that it only proves the default empty source, not configured fixture ingestion:
+
+```powershell
+powershell -NoProfile -ExecutionPolicy Bypass -File scripts/verify-go-mcp.ps1
+```
+
+Expected: PASS with `receive_message_count: 0`, but no configured-source proof yet.
+
+- [ ] **Step 2: Update the temporary Go harness**
+
+Extend the generated harness with a second server session that sets `ISPHERE_PACKET_LOG_FILE` to a temp synthetic encrypted log-line file and asserts one returned message with redacted content.
+
+- [ ] **Step 3: Update docs**
+
+Update the runbook/status card to say verification covers both default empty source and synthetic configured-source 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 C6 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.