fix(claude): projected sessions with thinking blocks are resumable again

CHANGELOG.md

@@ -2,6 +2,26 @@
 
 All notable changes to the Toolpath workspace are documented here.
 
+## Projected Claude sessions are resumable again — 2026-07-30
+
+Two fixes found by live-resuming a projected session against the real
+API. Together they broke resume for most projected sessions.
+
+- **`toolpath-claude`** (0.12.2): `ContentPart::Thinking` serializes a
+  `None` signature as an **absent key** instead of `"signature": null`.
+  The Anthropic API rejects a null signature outright
+  (`400 …thinking.signature.str: Input should be a valid string`), so
+  any projected session containing thinking blocks — most real agent
+  sessions — failed on the first message after resume. An absent
+  signature is tolerated: the thinking block is dropped on replay, per
+  the documented writer contract in
+  `docs/agents/formats/claude-code/writing-compatible-jsonl.md`. Real
+  signatures still round-trip untouched.
+- **`path-cli`** (0.16.1): the Claude JSONL export now ends
+  with a trailing newline. Claude Code appends to the projected file on
+  resume, and without one the first appended entry landed on the same
+  line as the last projected entry, corrupting the JSONL.
+
 ## `path p cache sync` — incremental session ingestion — 2026-07-16
 
 Adds `path p cache sync [types…]`, the first step toward a cache that

Cargo.toml

@@ -27,7 +27,7 @@ license = "Apache-2.0"
 toolpath = { version = "0.7.0", path = "crates/toolpath" }
 toolpath-convo = { version = "0.11.1", path = "crates/toolpath-convo" }
 toolpath-git = { version = "0.6.0", path = "crates/toolpath-git" }
-toolpath-claude = { version = "0.12.1", path = "crates/toolpath-claude", default-features = false }
+toolpath-claude = { version = "0.12.2", path = "crates/toolpath-claude", default-features = false }
 toolpath-gemini = { version = "0.6.1", path = "crates/toolpath-gemini", default-features = false }
 toolpath-codex = { version = "0.6.1", path = "crates/toolpath-codex" }
 toolpath-copilot = { version = "0.1.0", path = "crates/toolpath-copilot" }
@@ -37,7 +37,7 @@ toolpath-github = { version = "0.6.0", path = "crates/toolpath-github" }
 toolpath-dot = { version = "0.5.0", path = "crates/toolpath-dot" }
 toolpath-md = { version = "0.7.0", path = "crates/toolpath-md" }
 toolpath-pi = { version = "0.6.1", path = "crates/toolpath-pi" }
-path-cli = { version = "0.16.0", path = "crates/path-cli" }
+path-cli = { version = "0.16.1", path = "crates/path-cli" }
 pathbase-client = { version = "0.2.0", path = "crates/pathbase-client" }
 
 reqwest = { version = "0.13", default-features = false, features = ["blocking", "json", "rustls"] }

crates/path-cli/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "path-cli"
-version = "0.16.0"
+version = "0.16.1"
 edition.workspace = true
 license.workspace = true
 repository = "https://github.com/empathic/toolpath"

crates/path-cli/src/cmd_export.rs

@@ -684,7 +684,11 @@ fn serialize_jsonl(conv: &toolpath_claude::Conversation) -> Result<String> {
     for entry in &conv.entries {
         lines.push(serde_json::to_string(entry)?);
     }
-    Ok(lines.join("\n"))
+    // Trailing newline matters: Claude Code appends to this file on resume,
+    // and without it the first appended entry lands on the last line.
+    let mut out = lines.join("\n");
+    out.push('\n');
+    Ok(out)
 }
 
 #[cfg(not(target_os = "emscripten"))]

crates/toolpath-claude/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "toolpath-claude"
-version = "0.12.1"
+version = "0.12.2"
 edition.workspace = true
 license.workspace = true
 repository = "https://github.com/empathic/toolpath"

crates/toolpath-claude/src/types.rs

@@ -97,7 +97,11 @@ pub enum ContentPart {
     },
     Thinking {
         thinking: String,
-        #[serde(default)]
+        // Serialized as absent when None: the Anthropic API rejects
+        // `"signature": null` outright (400), while an absent signature just
+        // means the thinking block is dropped on resume — see
+        // docs/agents/formats/claude-code/writing-compatible-jsonl.md.
+        #[serde(default, skip_serializing_if = "Option::is_none")]
         signature: Option<String>,
     },
     ToolUse {
@@ -731,6 +735,27 @@ mod tests {
         assert_eq!(part.summary(), "[thinking]");
     }
 
+    #[test]
+    fn test_thinking_none_signature_serializes_absent() {
+        let part = ContentPart::Thinking {
+            thinking: "deep thought".to_string(),
+            signature: None,
+        };
+        let json = serde_json::to_value(&part).unwrap();
+        assert!(
+            json.get("signature").is_none(),
+            "None signature must serialize as an absent key, not null: the \
+             API 400s on `\"signature\": null` but tolerates absence"
+        );
+
+        let signed = ContentPart::Thinking {
+            thinking: "deep thought".to_string(),
+            signature: Some("sig123".to_string()),
+        };
+        let json = serde_json::to_value(&signed).unwrap();
+        assert_eq!(json.get("signature").unwrap(), "sig123");
+    }
+
     #[test]
     fn test_content_part_summary_tool_use() {
         let part = ContentPart::ToolUse {

crates/toolpath-cli/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "toolpath-cli"
-version = "0.16.0"
+version = "0.16.1"
 edition = "2024"
 license = "Apache-2.0"
 repository = "https://github.com/empathic/toolpath"
@@ -14,7 +14,7 @@ name = "path"
 path = "src/main.rs"
 
 [dependencies]
-path-cli = { path = "../path-cli", version = "0.16.0" }
+path-cli = { path = "../path-cli", version = "0.16.1" }
 anyhow = "1.0"
 
 [workspace]

site/_data/crates.json

@@ -33,7 +33,7 @@
   },
   {
     "name": "toolpath-claude",
-    "version": "0.12.1",
+    "version": "0.12.2",
     "description": "Derive from Claude conversation logs",
     "docs": "https://docs.rs/toolpath-claude",
     "crate": "https://crates.io/crates/toolpath-claude",
@@ -113,15 +113,15 @@
   },
   {
     "name": "path-cli",
-    "version": "0.16.0",
+    "version": "0.16.1",
     "description": "Unified CLI (binary: path)",
     "docs": "https://docs.rs/path-cli",
     "crate": "https://crates.io/crates/path-cli",
     "role": "One binary called `path` that ties everything together. Porcelain at the top level (share, resume, query, show, track, auth); plumbing under `path p \u2026` (import, export, cache, list, render, merge, validate). Pathbase round-trip via `p import pathbase` / `p export pathbase` (authed default \u2192 secret pathstash; anon fallback when not logged in)."
   },
   {
     "name": "toolpath-cli",
-    "version": "0.16.0",
+    "version": "0.16.1",
     "description": "Deprecated alias for path-cli",
     "docs": "https://docs.rs/toolpath-cli",
     "crate": "https://crates.io/crates/toolpath-cli",