diff --git a/.gitignore b/.gitignore
index 534f481..ab1f938 100644
--- a/.gitignore
+++ b/.gitignore
@@ -15,3 +15,4 @@ sds.nims
 nimble.develop
 nimble.paths
 nimbledeps
+.claude/**
diff --git a/AGENTS.md b/AGENTS.md
new file mode 100644
index 0000000..84d8372
--- /dev/null
+++ b/AGENTS.md
@@ -0,0 +1,43 @@
+<!-- gitnexus:start -->
+# GitNexus — Code Intelligence
+
+This project is indexed by GitNexus as **nim-sds** (889 symbols, 1437 relationships, 45 execution flows). Use the GitNexus MCP tools to understand code, assess impact, and navigate safely.
+
+> If any GitNexus tool warns the index is stale, run `npx gitnexus analyze` in terminal first.
+
+## Always Do
+
+- **MUST run impact analysis before editing any symbol.** Before modifying a function, class, or method, run `gitnexus_impact({target: "symbolName", direction: "upstream"})` and report the blast radius (direct callers, affected processes, risk level) to the user.
+- **MUST run `gitnexus_detect_changes()` before committing** to verify your changes only affect expected symbols and execution flows.
+- **MUST warn the user** if impact analysis returns HIGH or CRITICAL risk before proceeding with edits.
+- When exploring unfamiliar code, use `gitnexus_query({query: "concept"})` to find execution flows instead of grepping. It returns process-grouped results ranked by relevance.
+- When you need full context on a specific symbol — callers, callees, which execution flows it participates in — use `gitnexus_context({name: "symbolName"})`.
+
+## Never Do
+
+- NEVER edit a function, class, or method without first running `gitnexus_impact` on it.
+- NEVER ignore HIGH or CRITICAL risk warnings from impact analysis.
+- NEVER rename symbols with find-and-replace — use `gitnexus_rename` which understands the call graph.
+- NEVER commit changes without running `gitnexus_detect_changes()` to check affected scope.
+
+## Resources
+
+| Resource | Use for |
+|----------|---------|
+| `gitnexus://repo/nim-sds/context` | Codebase overview, check index freshness |
+| `gitnexus://repo/nim-sds/clusters` | All functional areas |
+| `gitnexus://repo/nim-sds/processes` | All execution flows |
+| `gitnexus://repo/nim-sds/process/{name}` | Step-by-step execution trace |
+
+## CLI
+
+| Task | Read this skill file |
+|------|---------------------|
+| Understand architecture / "How does X work?" | `.claude/skills/gitnexus/gitnexus-exploring/SKILL.md` |
+| Blast radius / "What breaks if I change X?" | `.claude/skills/gitnexus/gitnexus-impact-analysis/SKILL.md` |
+| Trace bugs / "Why is X failing?" | `.claude/skills/gitnexus/gitnexus-debugging/SKILL.md` |
+| Rename / extract / split / refactor | `.claude/skills/gitnexus/gitnexus-refactoring/SKILL.md` |
+| Tools, resources, schema reference | `.claude/skills/gitnexus/gitnexus-guide/SKILL.md` |
+| Index, status, clean, wiki CLI commands | `.claude/skills/gitnexus/gitnexus-cli/SKILL.md` |
+
+<!-- gitnexus:end -->
\ No newline at end of file
diff --git a/CLAUDE.md b/CLAUDE.md
index 0c6c90a..1df91d7 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -162,3 +162,47 @@ nimble lock              # update lock after changing sds.nimble
 ```
 
 If using Nix, also recalculate the fixed-output hash in `nix/deps.nix` after updating `nimble.lock` (run `nix build`, copy the expected hash from the error, paste into `outputHash`).
+
+<!-- gitnexus:start -->
+# GitNexus — Code Intelligence
+
+This project is indexed by GitNexus as **nim-sds** (889 symbols, 1437 relationships, 45 execution flows). Use the GitNexus MCP tools to understand code, assess impact, and navigate safely.
+
+> If any GitNexus tool warns the index is stale, run `npx gitnexus analyze` in terminal first.
+
+## Always Do
+
+- **MUST run impact analysis before editing any symbol.** Before modifying a function, class, or method, run `gitnexus_impact({target: "symbolName", direction: "upstream"})` and report the blast radius (direct callers, affected processes, risk level) to the user.
+- **MUST run `gitnexus_detect_changes()` before committing** to verify your changes only affect expected symbols and execution flows.
+- **MUST warn the user** if impact analysis returns HIGH or CRITICAL risk before proceeding with edits.
+- When exploring unfamiliar code, use `gitnexus_query({query: "concept"})` to find execution flows instead of grepping. It returns process-grouped results ranked by relevance.
+- When you need full context on a specific symbol — callers, callees, which execution flows it participates in — use `gitnexus_context({name: "symbolName"})`.
+
+## Never Do
+
+- NEVER edit a function, class, or method without first running `gitnexus_impact` on it.
+- NEVER ignore HIGH or CRITICAL risk warnings from impact analysis.
+- NEVER rename symbols with find-and-replace — use `gitnexus_rename` which understands the call graph.
+- NEVER commit changes without running `gitnexus_detect_changes()` to check affected scope.
+
+## Resources
+
+| Resource | Use for |
+|----------|---------|
+| `gitnexus://repo/nim-sds/context` | Codebase overview, check index freshness |
+| `gitnexus://repo/nim-sds/clusters` | All functional areas |
+| `gitnexus://repo/nim-sds/processes` | All execution flows |
+| `gitnexus://repo/nim-sds/process/{name}` | Step-by-step execution trace |
+
+## CLI
+
+| Task | Read this skill file |
+|------|---------------------|
+| Understand architecture / "How does X work?" | `.claude/skills/gitnexus/gitnexus-exploring/SKILL.md` |
+| Blast radius / "What breaks if I change X?" | `.claude/skills/gitnexus/gitnexus-impact-analysis/SKILL.md` |
+| Trace bugs / "Why is X failing?" | `.claude/skills/gitnexus/gitnexus-debugging/SKILL.md` |
+| Rename / extract / split / refactor | `.claude/skills/gitnexus/gitnexus-refactoring/SKILL.md` |
+| Tools, resources, schema reference | `.claude/skills/gitnexus/gitnexus-guide/SKILL.md` |
+| Index, status, clean, wiki CLI commands | `.claude/skills/gitnexus/gitnexus-cli/SKILL.md` |
+
+<!-- gitnexus:end -->
diff --git a/sds.nim b/sds.nim
index 29e4a2f..2e16c74 100644
--- a/sds.nim
+++ b/sds.nim
@@ -35,7 +35,7 @@ proc isAcknowledged*(
 
 proc reviewAckStatus(
     rm: ReliabilityManager, msg: SdsMessage
-): Future[void] {.async: (raises: []), gcsafe.} =
+): Future[void] {.async: (raises: [CatchableError]), gcsafe.} =
   try:
     var rbf: Option[RollingBloomFilter]
     if msg.bloomFilter.len > 0:
@@ -76,8 +76,9 @@ proc reviewAckStatus(
       let (idx, ackedId) = toDelete[k]
       channel.outgoingBuffer.delete(idx)
       await rm.persistence.removeOutgoing(msg.channelId, ackedId)
-  except CatchableError:
+  except CatchableError as e:
     error "Failed to review ack status", msg = getCurrentExceptionMsg()
+    raise e
 
 proc wrapOutgoingMessage*(
     rm: ReliabilityManager,
@@ -162,7 +163,7 @@ proc wrapOutgoingMessage*(
 
 proc processIncomingBuffer(
     rm: ReliabilityManager, channelId: SdsChannelID
-): Future[void] {.async: (raises: []), gcsafe.} =
+): Future[void] {.async: (raises: [CatchableError]), gcsafe.} =
   try:
     await rm.lock.acquire()
     try:
@@ -208,9 +209,10 @@ proc processIncomingBuffer(
         await rm.persistence.removeIncoming(channelId, msgId)
     finally:
       rm.lock.release()
-  except CatchableError:
+  except CatchableError as e:
     error "Failed to process incoming buffer",
       channelId = channelId, msg = getCurrentExceptionMsg()
+    raise e
 
 proc unwrapReceivedMessage*(
     rm: ReliabilityManager, message: seq[byte]
diff --git a/tests/test_bloom b/tests/test_bloom
new file mode 100755
index 0000000..ed43b69
Binary files /dev/null and b/tests/test_bloom differ
diff --git a/tests/test_persistence b/tests/test_persistence
new file mode 100755
index 0000000..69d512c
Binary files /dev/null and b/tests/test_persistence differ