diff --git a/CHANGELOG.md b/CHANGELOG.md
index c85e952..f7753e5 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -17,6 +17,7 @@
 - Session-status policy is now centralized in a single module that classifies every `SessionStatus` as active, terminal, commandable, live-host eligible, offline-replay eligible, collectable, and destroyed; lifecycle, inspect, gc, wait, host, and command-state checks share the same predicates. CLI JSON, protocol schemas, event-log behavior, and artifact formats are unchanged ([#67](https://github.com/coder/agent-tty/pull/67)).
 - Persisted event-log validation, JSONL parsing, and contiguous-sequence checks for live hydration, offline replay, and `record export` now flow through a shared codec at `src/storage/eventLogCodec.ts`. Validation errors use neutral event-log wording; missing-log policy remains caller-specific (offline replay treats missing logs as empty; `record export` still surfaces missing logs as an error) ([#68](https://github.com/coder/agent-tty/pull/68)).
 - Snapshot result construction and artifact persistence are now shared between live host RPCs and offline replay through `src/snapshot/capture.ts`. Snapshot artifact filenames, JSON formatting (two-space indent + trailing newline), manifest metadata, and `rendererBackend` reporting are unchanged ([#69](https://github.com/coder/agent-tty/pull/69)).
+- Screenshot capture, validation, and artifact persistence are now shared between live host RPCs and offline replay through `src/screenshot/capture.ts`. The shared seam owns temporary-file allocation, renderer screenshot invocation, allowlisted public result construction, Zod validation before any rename or manifest append, manifest metadata creation, and temp-file cleanup on failure. Screenshot filenames, final PNG paths, manifest entry shape (`profileName`, `cols`, `rows`, `pngSizeBytes`, `cursorVisible`, `rendererBackend`, `pixelWidth`, `pixelHeight`, `sha256`, `renderProfileHash`), and `screenshot --json` output are unchanged ([#78](https://github.com/coder/agent-tty/pull/78)).
 - Waited-run completion bookkeeping (sentinel scanning, postamble sanitization, waiter resolution, timeout, exit, `run_complete` appends) moved out of `hostMain` into a dedicated `RunCompletionCoordinator`. No public CLI, protocol, or event-log changes ([#70](https://github.com/coder/agent-tty/pull/70)).
 - Refreshed contributor and agent guidance in `AGENTS.md` with an outcome-first operating contract, validation guidance, and grouped project invariants ([#46](https://github.com/coder/agent-tty/pull/46)). Added in-repo agent skills under `.agents/skills/` (`diagnose`, `tdd`, `triage`, `improve-codebase-architecture`, `grill-with-docs`, `to-issues`, `to-prd`) plus matching links from `.claude/skills/` and `.mux/skills/` ([#65](https://github.com/coder/agent-tty/pull/65)).
 
diff --git a/CONTEXT.md b/CONTEXT.md
index 20870a7..0fcb703 100644
--- a/CONTEXT.md
+++ b/CONTEXT.md
@@ -69,6 +69,16 @@ A persisted JSON artifact containing exactly the **Snapshot Result** returned to
 The operation that derives a **Snapshot Result** from a **Semantic Snapshot** and records the matching **Snapshot Artifact**.
 _Avoid_: Renderer capture
 
+**Screenshot Result**:
+A public screenshot payload returned to a caller describing the rendered PNG of a **Session** at a captured event-log sequence.
+
+**Screenshot Artifact**:
+A persisted PNG file plus its manifest entry recording the **Screenshot Result** for a **Session** at a captured event-log sequence.
+
+**Screenshot Capture**:
+The operation that invokes the renderer to produce the PNG, builds the **Screenshot Result**, and records the matching **Screenshot Artifact**.
+_Avoid_: Renderer capture
+
 **Release Prep Workflow**:
 The maintainer-facing process for choosing the next release version and preparing release changes for review before they land on the default branch.
 
@@ -90,6 +100,8 @@ The tag-triggered automation that validates, packages, and publishes a release a
 - An **Offline Replay Eligible Session** is reconstructed from its persisted **Event Log** and manifest.
 - A **Snapshot Result** is derived from exactly one **Semantic Snapshot**.
 - A **Snapshot Artifact** contains exactly the **Snapshot Result** emitted to the caller.
+- A **Screenshot Capture** produces exactly one **Screenshot Result** and exactly one **Screenshot Artifact** for the same captured event-log sequence.
+- A **Screenshot Artifact** is the persisted PNG plus its manifest entry that the **Screenshot Result** describes to the caller.
 - A **Command Target** is exactly one **Commandable Session** selected by an input or control command.
 - A **Commandable Session** can accept a **Waited Run**.
 - A **Render Wait** may include text, regex, cursor, or **Screen Stability** conditions.
diff --git a/dogfood/issue-64-share-screenshot-capture/README.md b/dogfood/issue-64-share-screenshot-capture/README.md
new file mode 100644
index 0000000..4ca3623
--- /dev/null
+++ b/dogfood/issue-64-share-screenshot-capture/README.md
@@ -0,0 +1,95 @@
+# Issue 64 — Share screenshot capture and artifact persistence
+
+This bundle compares screenshot output from the running session (live) and
+exited session (offline replay) paths, before and after the refactor that
+moves both paths through the shared `captureScreenshotResult(...)` helper in
+`src/screenshot/capture.ts`.
+
+## How it was generated
+
+The same `commands.sh` was run twice:
+
+1. **before**: against parent commit `b2d5068` (`refactor: share render wait
+matching (#76)`) in a temporary `git worktree`. This still has the
+   inline screenshot logic in `src/host/hostMain.ts` and a duplicate
+   implementation in `src/cli/commands/screenshot.ts`.
+2. **after**: against this branch, where both paths call the new
+   `captureScreenshotResult(...)` helper.
+
+Each run uses an isolated absolute `AGENT_TTY_HOME` (recorded in
+`<label>/agent-tty-home.txt`) and writes its outputs under
+`<label>/`.
+
+The script is idempotent and safe to re-run:
+
+```sh
+bash dogfood/issue-64-share-screenshot-capture/commands.sh after
+# or, in a worktree of the parent commit:
+bash dogfood/issue-64-share-screenshot-capture/commands.sh before
+```
+
+## Scenarios captured
+
+For both `before/` and `after/` directories:
+
+| File                                     | Description                                         |
+| ---------------------------------------- | --------------------------------------------------- |
+| `03-screenshot-live-default.json`        | Live (running) screenshot, default cursor           |
+| `04-screenshot-live-show-cursor.json`    | Live (running) screenshot with `--show-cursor`      |
+| `12-screenshot-offline-default.json`     | Offline (exited) screenshot, default cursor         |
+| `13-screenshot-offline-show-cursor.json` | Offline (exited) screenshot with `--show-cursor`    |
+| `screenshot-live-default.png`            | Live default-cursor PNG                             |
+| `screenshot-live-show-cursor.png`        | Live show-cursor PNG                                |
+| `screenshot-offline-default.png`         | Offline default-cursor PNG                          |
+| `screenshot-offline-show-cursor.png`     | Offline show-cursor PNG                             |
+| `manifest-live.json`                     | Artifact manifest after live session screenshots    |
+| `manifest-offline.json`                  | Artifact manifest after offline session screenshots |
+| `sha256-summary.txt`                     | One-line-per-PNG SHA-256 summary                    |
+| `transcript.txt`                         | Full command transcript                             |
+
+Default profile is `reference-dark` (the only profile this refactor needs to
+preserve).
+
+## Parity verdict
+
+| Comparison                                                                                                                           | Result                 |
+| ------------------------------------------------------------------------------------------------------------------------------------ | ---------------------- |
+| `sha256-summary.txt` (live + offline, with and without cursor)                                                                       | **identical**          |
+| All four screenshot result envelopes, excluding session IDs and the absolute `artifactPath` (which embeds the temp `AGENT_TTY_HOME`) | **identical fields**   |
+| Artifact manifest entries, excluding ULID `id`, `sessionId`, and `createdAt` timestamps                                              | **identical metadata** |
+| All four PNG files, byte-for-byte (`cmp -s`)                                                                                         | **identical bytes**    |
+
+Specifically:
+
+- Live default and live show-cursor PNGs both hash to
+  `a658e720e18b2943fd6203e8947a9fe4e60fa0759cb5d0f9c74668abfe267ceb` in both
+  before and after.
+- Offline default and offline show-cursor PNGs both hash to
+  `993fb5f9fe5b9ec7ed456b4005ec40478f5ee6bc3c6d5a65f6dbc78fbd60406d` in both
+  before and after.
+- All result envelopes preserve `profileName=reference-dark`,
+  `cols=80`, `rows=24`, `pngSizeBytes`, `pixelWidth=640`, `pixelHeight=384`,
+  `cursorVisible`, `rendererBackend=ghostty-web`, and `renderProfileHash`.
+
+## Reviewer reproduction
+
+To independently verify these comparisons:
+
+```sh
+node -e "
+  const fs = require('node:fs');
+  function strip(p) {
+    const e = JSON.parse(fs.readFileSync(p, 'utf8'));
+    const r = e.result; delete r.sessionId; delete r.artifactPath;
+    delete e.timestamp;
+    return e;
+  }
+  for (const f of ['03-screenshot-live-default','04-screenshot-live-show-cursor','12-screenshot-offline-default','13-screenshot-offline-show-cursor']) {
+    const a = strip(\`before/\${f}.json\`);
+    const b = strip(\`after/\${f}.json\`);
+    console.log(f, JSON.stringify(a)===JSON.stringify(b) ? 'IDENTICAL' : 'DIFFER');
+  }
+"
+cmp -s before/screenshot-live-default.png after/screenshot-live-default.png && echo "live-default PNG IDENTICAL"
+cmp -s before/screenshot-offline-default.png after/screenshot-offline-default.png && echo "offline-default PNG IDENTICAL"
+```
diff --git a/dogfood/issue-64-share-screenshot-capture/after/01-create-live.json b/dogfood/issue-64-share-screenshot-capture/after/01-create-live.json
new file mode 100644
index 0000000..1f2cc8b
--- /dev/null
+++ b/dogfood/issue-64-share-screenshot-capture/after/01-create-live.json
@@ -0,0 +1,12 @@
+{
+  "ok": true,
+  "command": "create",
+  "timestamp": "2026-04-30T07:53:01.428Z",
+  "result": {
+    "sessionId": "01KQEP0YDSTXK6A7EB7ABAK8SS",
+    "createdAt": "2026-04-30T07:53:00.604Z",
+    "cols": 80,
+    "rows": 24,
+    "shell": "/bin/bash"
+  }
+}
diff --git a/dogfood/issue-64-share-screenshot-capture/after/02-wait-live.json b/dogfood/issue-64-share-screenshot-capture/after/02-wait-live.json
new file mode 100644
index 0000000..481d0d4
--- /dev/null
+++ b/dogfood/issue-64-share-screenshot-capture/after/02-wait-live.json
@@ -0,0 +1,13 @@
+{
+  "ok": true,
+  "command": "wait",
+  "timestamp": "2026-04-30T07:53:03.114Z",
+  "result": {
+    "matched": true,
+    "timedOut": false,
+    "matchedText": "live screenshot fixture",
+    "cursorRow": 1,
+    "cursorCol": 0,
+    "capturedAtSeq": 0
+  }
+}
diff --git a/dogfood/issue-64-share-screenshot-capture/after/03-screenshot-live-default.json b/dogfood/issue-64-share-screenshot-capture/after/03-screenshot-live-default.json
new file mode 100644
index 0000000..e17584f
--- /dev/null
+++ b/dogfood/issue-64-share-screenshot-capture/after/03-screenshot-live-default.json
@@ -0,0 +1,20 @@
+{
+  "ok": true,
+  "command": "screenshot",
+  "timestamp": "2026-04-30T07:53:04.412Z",
+  "result": {
+    "sessionId": "01KQEP0YDSTXK6A7EB7ABAK8SS",
+    "capturedAtSeq": 0,
+    "profileName": "reference-dark",
+    "cols": 80,
+    "rows": 24,
+    "artifactPath": "/tmp/tmp.p97cQahYjP/sessions/01KQEP0YDSTXK6A7EB7ABAK8SS/artifacts/screenshot-0-reference-dark.png",
+    "pngSizeBytes": 3790,
+    "cursorVisible": false,
+    "rendererBackend": "ghostty-web",
+    "pixelWidth": 640,
+    "pixelHeight": 384,
+    "sha256": "a658e720e18b2943fd6203e8947a9fe4e60fa0759cb5d0f9c74668abfe267ceb",
+    "renderProfileHash": "8ffed6af301ec7c0e6b69599c3be0d1d12096f9fcdfc59d0bbb4cc474d64c53d"
+  }
+}
diff --git a/dogfood/issue-64-share-screenshot-capture/after/04-screenshot-live-show-cursor.json b/dogfood/issue-64-share-screenshot-capture/after/04-screenshot-live-show-cursor.json
new file mode 100644
index 0000000..7cb9542
--- /dev/null
+++ b/dogfood/issue-64-share-screenshot-capture/after/04-screenshot-live-show-cursor.json
@@ -0,0 +1,20 @@
+{
+  "ok": true,
+  "command": "screenshot",
+  "timestamp": "2026-04-30T07:53:05.670Z",
+  "result": {
+    "sessionId": "01KQEP0YDSTXK6A7EB7ABAK8SS",
+    "capturedAtSeq": 0,
+    "profileName": "reference-dark",
+    "cols": 80,
+    "rows": 24,
+    "artifactPath": "/tmp/tmp.p97cQahYjP/sessions/01KQEP0YDSTXK6A7EB7ABAK8SS/artifacts/screenshot-0-reference-dark.png",
+    "pngSizeBytes": 3790,
+    "cursorVisible": true,
+    "rendererBackend": "ghostty-web",
+    "pixelWidth": 640,
+    "pixelHeight": 384,
+    "sha256": "a658e720e18b2943fd6203e8947a9fe4e60fa0759cb5d0f9c74668abfe267ceb",
+    "renderProfileHash": "8ffed6af301ec7c0e6b69599c3be0d1d12096f9fcdfc59d0bbb4cc474d64c53d"
+  }
+}
diff --git a/dogfood/issue-64-share-screenshot-capture/after/10-create-offline.json b/dogfood/issue-64-share-screenshot-capture/after/10-create-offline.json
new file mode 100644
index 0000000..5701e44
--- /dev/null
+++ b/dogfood/issue-64-share-screenshot-capture/after/10-create-offline.json
@@ -0,0 +1,12 @@
+{
+  "ok": true,
+  "command": "create",
+  "timestamp": "2026-04-30T07:53:07.504Z",
+  "result": {
+    "sessionId": "01KQEP14EXSSGJX9RRSTAVYGK2",
+    "createdAt": "2026-04-30T07:53:06.784Z",
+    "cols": 80,
+    "rows": 24,
+    "shell": "/bin/bash"
+  }
+}
diff --git a/dogfood/issue-64-share-screenshot-capture/after/11-wait-offline.json b/dogfood/issue-64-share-screenshot-capture/after/11-wait-offline.json
new file mode 100644
index 0000000..b6b4836
--- /dev/null
+++ b/dogfood/issue-64-share-screenshot-capture/after/11-wait-offline.json
@@ -0,0 +1,9 @@
+{
+  "ok": true,
+  "command": "wait",
+  "timestamp": "2026-04-30T07:53:08.644Z",
+  "result": {
+    "timedOut": false,
+    "exitCode": 0
+  }
+}
diff --git a/dogfood/issue-64-share-screenshot-capture/after/12-screenshot-offline-default.json b/dogfood/issue-64-share-screenshot-capture/after/12-screenshot-offline-default.json
new file mode 100644
index 0000000..5487628
--- /dev/null
+++ b/dogfood/issue-64-share-screenshot-capture/after/12-screenshot-offline-default.json
@@ -0,0 +1,20 @@
+{
+  "ok": true,
+  "command": "screenshot",
+  "timestamp": "2026-04-30T07:53:10.283Z",
+  "result": {
+    "sessionId": "01KQEP14EXSSGJX9RRSTAVYGK2",
+    "capturedAtSeq": 1,
+    "profileName": "reference-dark",
+    "cols": 80,
+    "rows": 24,
+    "artifactPath": "/tmp/tmp.p97cQahYjP/sessions/01KQEP14EXSSGJX9RRSTAVYGK2/artifacts/screenshot-1-reference-dark.png",
+    "pngSizeBytes": 3749,
+    "cursorVisible": false,
+    "rendererBackend": "ghostty-web",
+    "pixelWidth": 640,
+    "pixelHeight": 384,
+    "sha256": "993fb5f9fe5b9ec7ed456b4005ec40478f5ee6bc3c6d5a65f6dbc78fbd60406d",
+    "renderProfileHash": "8ffed6af301ec7c0e6b69599c3be0d1d12096f9fcdfc59d0bbb4cc474d64c53d"
+  }
+}
diff --git a/dogfood/issue-64-share-screenshot-capture/after/13-screenshot-offline-show-cursor.json b/dogfood/issue-64-share-screenshot-capture/after/13-screenshot-offline-show-cursor.json
new file mode 100644
index 0000000..d1e357e
--- /dev/null
+++ b/dogfood/issue-64-share-screenshot-capture/after/13-screenshot-offline-show-cursor.json
@@ -0,0 +1,20 @@
+{
+  "ok": true,
+  "command": "screenshot",
+  "timestamp": "2026-04-30T07:53:16.766Z",
+  "result": {
+    "sessionId": "01KQEP14EXSSGJX9RRSTAVYGK2",
+    "capturedAtSeq": 1,
+    "profileName": "reference-dark",
+    "cols": 80,
+    "rows": 24,
+    "artifactPath": "/tmp/tmp.p97cQahYjP/sessions/01KQEP14EXSSGJX9RRSTAVYGK2/artifacts/screenshot-1-reference-dark.png",
+    "pngSizeBytes": 3749,
+    "cursorVisible": true,
+    "rendererBackend": "ghostty-web",
+    "pixelWidth": 640,
+    "pixelHeight": 384,
+    "sha256": "993fb5f9fe5b9ec7ed456b4005ec40478f5ee6bc3c6d5a65f6dbc78fbd60406d",
+    "renderProfileHash": "8ffed6af301ec7c0e6b69599c3be0d1d12096f9fcdfc59d0bbb4cc474d64c53d"
+  }
+}
diff --git a/dogfood/issue-64-share-screenshot-capture/after/98-destroy-offline.json b/dogfood/issue-64-share-screenshot-capture/after/98-destroy-offline.json
new file mode 100644
index 0000000..edb602e
--- /dev/null
+++ b/dogfood/issue-64-share-screenshot-capture/after/98-destroy-offline.json
@@ -0,0 +1,9 @@
+{
+  "ok": true,
+  "command": "destroy",
+  "timestamp": "2026-04-30T07:53:24.099Z",
+  "result": {
+    "sessionId": "01KQEP14EXSSGJX9RRSTAVYGK2",
+    "destroyed": true
+  }
+}
diff --git a/dogfood/issue-64-share-screenshot-capture/after/99-destroy-live.json b/dogfood/issue-64-share-screenshot-capture/after/99-destroy-live.json
new file mode 100644
index 0000000..035c9a3
--- /dev/null
+++ b/dogfood/issue-64-share-screenshot-capture/after/99-destroy-live.json
@@ -0,0 +1,9 @@
+{
+  "ok": true,
+  "command": "destroy",
+  "timestamp": "2026-04-30T07:53:23.059Z",
+  "result": {
+    "sessionId": "01KQEP0YDSTXK6A7EB7ABAK8SS",
+    "destroyed": true
+  }
+}
diff --git a/dogfood/issue-64-share-screenshot-capture/after/agent-tty-home.txt b/dogfood/issue-64-share-screenshot-capture/after/agent-tty-home.txt
new file mode 100644
index 0000000..33214ac
--- /dev/null
+++ b/dogfood/issue-64-share-screenshot-capture/after/agent-tty-home.txt
@@ -0,0 +1 @@
+/tmp/tmp.p97cQahYjP
diff --git a/dogfood/issue-64-share-screenshot-capture/after/live-session-id.txt b/dogfood/issue-64-share-screenshot-capture/after/live-session-id.txt
new file mode 100644
index 0000000..3a8e47a
--- /dev/null
+++ b/dogfood/issue-64-share-screenshot-capture/after/live-session-id.txt
@@ -0,0 +1 @@
+01KQEP0YDSTXK6A7EB7ABAK8SS
diff --git a/dogfood/issue-64-share-screenshot-capture/after/manifest-live.json b/dogfood/issue-64-share-screenshot-capture/after/manifest-live.json
new file mode 100644
index 0000000..de0ffc8
--- /dev/null
+++ b/dogfood/issue-64-share-screenshot-capture/after/manifest-live.json
@@ -0,0 +1,46 @@
+{
+  "version": 1,
+  "sessionId": "01KQEP0YDSTXK6A7EB7ABAK8SS",
+  "artifacts": [
+    {
+      "id": "01KQEP124PSDQBCK39NM2JRG0Q",
+      "kind": "screenshot",
+      "filename": "screenshot-0-reference-dark.png",
+      "sessionId": "01KQEP0YDSTXK6A7EB7ABAK8SS",
+      "capturedAtSeq": 0,
+      "createdAt": "2026-04-30T07:53:04.406Z",
+      "sha256": "a658e720e18b2943fd6203e8947a9fe4e60fa0759cb5d0f9c74668abfe267ceb",
+      "metadata": {
+        "profileName": "reference-dark",
+        "cols": 80,
+        "rows": 24,
+        "pngSizeBytes": 3790,
+        "cursorVisible": false,
+        "rendererBackend": "ghostty-web",
+        "pixelWidth": 640,
+        "pixelHeight": 384,
+        "renderProfileHash": "8ffed6af301ec7c0e6b69599c3be0d1d12096f9fcdfc59d0bbb4cc474d64c53d"
+      }
+    },
+    {
+      "id": "01KQEP13C2VTX38AMZV3F92STZ",
+      "kind": "screenshot",
+      "filename": "screenshot-0-reference-dark.png",
+      "sessionId": "01KQEP0YDSTXK6A7EB7ABAK8SS",
+      "capturedAtSeq": 0,
+      "createdAt": "2026-04-30T07:53:05.667Z",
+      "sha256": "a658e720e18b2943fd6203e8947a9fe4e60fa0759cb5d0f9c74668abfe267ceb",
+      "metadata": {
+        "profileName": "reference-dark",
+        "cols": 80,
+        "rows": 24,
+        "pngSizeBytes": 3790,
+        "cursorVisible": true,
+        "rendererBackend": "ghostty-web",
+        "pixelWidth": 640,
+        "pixelHeight": 384,
+        "renderProfileHash": "8ffed6af301ec7c0e6b69599c3be0d1d12096f9fcdfc59d0bbb4cc474d64c53d"
+      }
+    }
+  ]
+}
diff --git a/dogfood/issue-64-share-screenshot-capture/after/manifest-offline.json b/dogfood/issue-64-share-screenshot-capture/after/manifest-offline.json
new file mode 100644
index 0000000..eaaa729
--- /dev/null
+++ b/dogfood/issue-64-share-screenshot-capture/after/manifest-offline.json
@@ -0,0 +1,46 @@
+{
+  "version": 1,
+  "sessionId": "01KQEP14EXSSGJX9RRSTAVYGK2",
+  "artifacts": [
+    {
+      "id": "01KQEP17V1X05S77G8CX5X7VPE",
+      "kind": "screenshot",
+      "filename": "screenshot-1-reference-dark.png",
+      "sessionId": "01KQEP14EXSSGJX9RRSTAVYGK2",
+      "capturedAtSeq": 1,
+      "createdAt": "2026-04-30T07:53:10.241Z",
+      "sha256": "993fb5f9fe5b9ec7ed456b4005ec40478f5ee6bc3c6d5a65f6dbc78fbd60406d",
+      "metadata": {
+        "profileName": "reference-dark",
+        "cols": 80,
+        "rows": 24,
+        "pngSizeBytes": 3749,
+        "cursorVisible": false,
+        "rendererBackend": "ghostty-web",
+        "pixelWidth": 640,
+        "pixelHeight": 384,
+        "renderProfileHash": "8ffed6af301ec7c0e6b69599c3be0d1d12096f9fcdfc59d0bbb4cc474d64c53d"
+      }
+    },
+    {
+      "id": "01KQEP1E5KMKCHYK9BEZJ6TD0G",
+      "kind": "screenshot",
+      "filename": "screenshot-1-reference-dark.png",
+      "sessionId": "01KQEP14EXSSGJX9RRSTAVYGK2",
+      "capturedAtSeq": 1,
+      "createdAt": "2026-04-30T07:53:16.723Z",
+      "sha256": "993fb5f9fe5b9ec7ed456b4005ec40478f5ee6bc3c6d5a65f6dbc78fbd60406d",
+      "metadata": {
+        "profileName": "reference-dark",
+        "cols": 80,
+        "rows": 24,
+        "pngSizeBytes": 3749,
+        "cursorVisible": true,
+        "rendererBackend": "ghostty-web",
+        "pixelWidth": 640,
+        "pixelHeight": 384,
+        "renderProfileHash": "8ffed6af301ec7c0e6b69599c3be0d1d12096f9fcdfc59d0bbb4cc474d64c53d"
+      }
+    }
+  ]
+}
diff --git a/dogfood/issue-64-share-screenshot-capture/after/offline-session-id.txt b/dogfood/issue-64-share-screenshot-capture/after/offline-session-id.txt
new file mode 100644
index 0000000..e9d1b19
--- /dev/null
+++ b/dogfood/issue-64-share-screenshot-capture/after/offline-session-id.txt
@@ -0,0 +1 @@
+01KQEP14EXSSGJX9RRSTAVYGK2
diff --git a/dogfood/issue-64-share-screenshot-capture/after/screenshot-live-default.png b/dogfood/issue-64-share-screenshot-capture/after/screenshot-live-default.png
new file mode 100644
index 0000000..376bebc
Binary files /dev/null and b/dogfood/issue-64-share-screenshot-capture/after/screenshot-live-default.png differ
diff --git a/dogfood/issue-64-share-screenshot-capture/after/screenshot-live-show-cursor.png b/dogfood/issue-64-share-screenshot-capture/after/screenshot-live-show-cursor.png
new file mode 100644
index 0000000..376bebc
Binary files /dev/null and b/dogfood/issue-64-share-screenshot-capture/after/screenshot-live-show-cursor.png differ
diff --git a/dogfood/issue-64-share-screenshot-capture/after/screenshot-offline-default.png b/dogfood/issue-64-share-screenshot-capture/after/screenshot-offline-default.png
new file mode 100644
index 0000000..2f9738b
Binary files /dev/null and b/dogfood/issue-64-share-screenshot-capture/after/screenshot-offline-default.png differ
diff --git a/dogfood/issue-64-share-screenshot-capture/after/screenshot-offline-show-cursor.png b/dogfood/issue-64-share-screenshot-capture/after/screenshot-offline-show-cursor.png
new file mode 100644
index 0000000..2f9738b
Binary files /dev/null and b/dogfood/issue-64-share-screenshot-capture/after/screenshot-offline-show-cursor.png differ
diff --git a/dogfood/issue-64-share-screenshot-capture/after/sha256-summary.txt b/dogfood/issue-64-share-screenshot-capture/after/sha256-summary.txt
new file mode 100644
index 0000000..3737de7
--- /dev/null
+++ b/dogfood/issue-64-share-screenshot-capture/after/sha256-summary.txt
@@ -0,0 +1,8 @@
+screenshot-live-default.png:
+a658e720e18b2943fd6203e8947a9fe4e60fa0759cb5d0f9c74668abfe267ceb
+screenshot-live-show-cursor.png:
+a658e720e18b2943fd6203e8947a9fe4e60fa0759cb5d0f9c74668abfe267ceb
+screenshot-offline-default.png:
+993fb5f9fe5b9ec7ed456b4005ec40478f5ee6bc3c6d5a65f6dbc78fbd60406d
+screenshot-offline-show-cursor.png:
+993fb5f9fe5b9ec7ed456b4005ec40478f5ee6bc3c6d5a65f6dbc78fbd60406d
diff --git a/dogfood/issue-64-share-screenshot-capture/after/transcript.txt b/dogfood/issue-64-share-screenshot-capture/after/transcript.txt
new file mode 100644
index 0000000..0c789bf
--- /dev/null
+++ b/dogfood/issue-64-share-screenshot-capture/after/transcript.txt
@@ -0,0 +1,152 @@
+Running with label: after
+Repo HEAD: b2d506802110a97ebd4cc8b985970a19211fd36b
++ npx tsx src/cli/main.ts create --json --name issue-64-live -- /bin/sh -c printf\ \"live\ screenshot\ fixture\\n\"\;\ sleep\ 60
+{
+  "ok": true,
+  "command": "create",
+  "timestamp": "2026-04-30T07:53:01.428Z",
+  "result": {
+    "sessionId": "01KQEP0YDSTXK6A7EB7ABAK8SS",
+    "createdAt": "2026-04-30T07:53:00.604Z",
+    "cols": 80,
+    "rows": 24,
+    "shell": "/bin/bash"
+  }
+}
+
++ npx tsx src/cli/main.ts wait 01KQEP0YDSTXK6A7EB7ABAK8SS --text live\ screenshot\ fixture --timeout 5000 --json
+{
+  "ok": true,
+  "command": "wait",
+  "timestamp": "2026-04-30T07:53:03.114Z",
+  "result": {
+    "matched": true,
+    "timedOut": false,
+    "matchedText": "live screenshot fixture",
+    "cursorRow": 1,
+    "cursorCol": 0,
+    "capturedAtSeq": 0
+  }
+}
+
++ npx tsx src/cli/main.ts screenshot 01KQEP0YDSTXK6A7EB7ABAK8SS --json
+{
+  "ok": true,
+  "command": "screenshot",
+  "timestamp": "2026-04-30T07:53:04.412Z",
+  "result": {
+    "sessionId": "01KQEP0YDSTXK6A7EB7ABAK8SS",
+    "capturedAtSeq": 0,
+    "profileName": "reference-dark",
+    "cols": 80,
+    "rows": 24,
+    "artifactPath": "/tmp/tmp.p97cQahYjP/sessions/01KQEP0YDSTXK6A7EB7ABAK8SS/artifacts/screenshot-0-reference-dark.png",
+    "pngSizeBytes": 3790,
+    "cursorVisible": false,
+    "rendererBackend": "ghostty-web",
+    "pixelWidth": 640,
+    "pixelHeight": 384,
+    "sha256": "a658e720e18b2943fd6203e8947a9fe4e60fa0759cb5d0f9c74668abfe267ceb",
+    "renderProfileHash": "8ffed6af301ec7c0e6b69599c3be0d1d12096f9fcdfc59d0bbb4cc474d64c53d"
+  }
+}
+
++ npx tsx src/cli/main.ts screenshot 01KQEP0YDSTXK6A7EB7ABAK8SS --show-cursor --json
+{
+  "ok": true,
+  "command": "screenshot",
+  "timestamp": "2026-04-30T07:53:05.670Z",
+  "result": {
+    "sessionId": "01KQEP0YDSTXK6A7EB7ABAK8SS",
+    "capturedAtSeq": 0,
+    "profileName": "reference-dark",
+    "cols": 80,
+    "rows": 24,
+    "artifactPath": "/tmp/tmp.p97cQahYjP/sessions/01KQEP0YDSTXK6A7EB7ABAK8SS/artifacts/screenshot-0-reference-dark.png",
+    "pngSizeBytes": 3790,
+    "cursorVisible": true,
+    "rendererBackend": "ghostty-web",
+    "pixelWidth": 640,
+    "pixelHeight": 384,
+    "sha256": "a658e720e18b2943fd6203e8947a9fe4e60fa0759cb5d0f9c74668abfe267ceb",
+    "renderProfileHash": "8ffed6af301ec7c0e6b69599c3be0d1d12096f9fcdfc59d0bbb4cc474d64c53d"
+  }
+}
+
++ npx tsx src/cli/main.ts create --json --name issue-64-offline -- /bin/sh -c printf\ \"offline\ screenshot\ fixture\\n\"
+{
+  "ok": true,
+  "command": "create",
+  "timestamp": "2026-04-30T07:53:07.504Z",
+  "result": {
+    "sessionId": "01KQEP14EXSSGJX9RRSTAVYGK2",
+    "createdAt": "2026-04-30T07:53:06.784Z",
+    "cols": 80,
+    "rows": 24,
+    "shell": "/bin/bash"
+  }
+}
+
++ npx tsx src/cli/main.ts wait 01KQEP14EXSSGJX9RRSTAVYGK2 --exit --timeout 10000 --json
+{
+  "ok": true,
+  "command": "wait",
+  "timestamp": "2026-04-30T07:53:08.644Z",
+  "result": {
+    "timedOut": false,
+    "exitCode": 0
+  }
+}
+
++ npx tsx src/cli/main.ts screenshot 01KQEP14EXSSGJX9RRSTAVYGK2 --json
+{
+  "ok": true,
+  "command": "screenshot",
+  "timestamp": "2026-04-30T07:53:10.283Z",
+  "result": {
+    "sessionId": "01KQEP14EXSSGJX9RRSTAVYGK2",
+    "capturedAtSeq": 1,
+    "profileName": "reference-dark",
+    "cols": 80,
+    "rows": 24,
+    "artifactPath": "/tmp/tmp.p97cQahYjP/sessions/01KQEP14EXSSGJX9RRSTAVYGK2/artifacts/screenshot-1-reference-dark.png",
+    "pngSizeBytes": 3749,
+    "cursorVisible": false,
+    "rendererBackend": "ghostty-web",
+    "pixelWidth": 640,
+    "pixelHeight": 384,
+    "sha256": "993fb5f9fe5b9ec7ed456b4005ec40478f5ee6bc3c6d5a65f6dbc78fbd60406d",
+    "renderProfileHash": "8ffed6af301ec7c0e6b69599c3be0d1d12096f9fcdfc59d0bbb4cc474d64c53d"
+  }
+}
+
++ npx tsx src/cli/main.ts screenshot 01KQEP14EXSSGJX9RRSTAVYGK2 --show-cursor --json
+{
+  "ok": true,
+  "command": "screenshot",
+  "timestamp": "2026-04-30T07:53:16.766Z",
+  "result": {
+    "sessionId": "01KQEP14EXSSGJX9RRSTAVYGK2",
+    "capturedAtSeq": 1,
+    "profileName": "reference-dark",
+    "cols": 80,
+    "rows": 24,
+    "artifactPath": "/tmp/tmp.p97cQahYjP/sessions/01KQEP14EXSSGJX9RRSTAVYGK2/artifacts/screenshot-1-reference-dark.png",
+    "pngSizeBytes": 3749,
+    "cursorVisible": true,
+    "rendererBackend": "ghostty-web",
+    "pixelWidth": 640,
+    "pixelHeight": 384,
+    "sha256": "993fb5f9fe5b9ec7ed456b4005ec40478f5ee6bc3c6d5a65f6dbc78fbd60406d",
+    "renderProfileHash": "8ffed6af301ec7c0e6b69599c3be0d1d12096f9fcdfc59d0bbb4cc474d64c53d"
+  }
+}
+
+screenshot-live-default.png:
+a658e720e18b2943fd6203e8947a9fe4e60fa0759cb5d0f9c74668abfe267ceb
+screenshot-live-show-cursor.png:
+a658e720e18b2943fd6203e8947a9fe4e60fa0759cb5d0f9c74668abfe267ceb
+screenshot-offline-default.png:
+993fb5f9fe5b9ec7ed456b4005ec40478f5ee6bc3c6d5a65f6dbc78fbd60406d
+screenshot-offline-show-cursor.png:
+993fb5f9fe5b9ec7ed456b4005ec40478f5ee6bc3c6d5a65f6dbc78fbd60406d
diff --git a/dogfood/issue-64-share-screenshot-capture/before/01-create-live.json b/dogfood/issue-64-share-screenshot-capture/before/01-create-live.json
new file mode 100644
index 0000000..0c2d134
--- /dev/null
+++ b/dogfood/issue-64-share-screenshot-capture/before/01-create-live.json
@@ -0,0 +1,12 @@
+{
+  "ok": true,
+  "command": "create",
+  "timestamp": "2026-04-30T07:54:21.162Z",
+  "result": {
+    "sessionId": "01KQEP3C9F2CMDX15SQWFTW9MK",
+    "createdAt": "2026-04-30T07:54:20.338Z",
+    "cols": 80,
+    "rows": 24,
+    "shell": "/bin/bash"
+  }
+}
diff --git a/dogfood/issue-64-share-screenshot-capture/before/02-wait-live.json b/dogfood/issue-64-share-screenshot-capture/before/02-wait-live.json
new file mode 100644
index 0000000..403c3d1
--- /dev/null
+++ b/dogfood/issue-64-share-screenshot-capture/before/02-wait-live.json
@@ -0,0 +1,13 @@
+{
+  "ok": true,
+  "command": "wait",
+  "timestamp": "2026-04-30T07:54:22.828Z",
+  "result": {
+    "matched": true,
+    "timedOut": false,
+    "matchedText": "live screenshot fixture",
+    "cursorRow": 1,
+    "cursorCol": 0,
+    "capturedAtSeq": 0
+  }
+}
diff --git a/dogfood/issue-64-share-screenshot-capture/before/03-screenshot-live-default.json b/dogfood/issue-64-share-screenshot-capture/before/03-screenshot-live-default.json
new file mode 100644
index 0000000..6cc54fd
--- /dev/null
+++ b/dogfood/issue-64-share-screenshot-capture/before/03-screenshot-live-default.json
@@ -0,0 +1,20 @@
+{
+  "ok": true,
+  "command": "screenshot",
+  "timestamp": "2026-04-30T07:54:24.088Z",
+  "result": {
+    "sessionId": "01KQEP3C9F2CMDX15SQWFTW9MK",
+    "capturedAtSeq": 0,
+    "profileName": "reference-dark",
+    "cols": 80,
+    "rows": 24,
+    "artifactPath": "/tmp/tmp.XjcTHC008g/sessions/01KQEP3C9F2CMDX15SQWFTW9MK/artifacts/screenshot-0-reference-dark.png",
+    "pngSizeBytes": 3790,
+    "cursorVisible": false,
+    "rendererBackend": "ghostty-web",
+    "pixelWidth": 640,
+    "pixelHeight": 384,
+    "sha256": "a658e720e18b2943fd6203e8947a9fe4e60fa0759cb5d0f9c74668abfe267ceb",
+    "renderProfileHash": "8ffed6af301ec7c0e6b69599c3be0d1d12096f9fcdfc59d0bbb4cc474d64c53d"
+  }
+}
diff --git a/dogfood/issue-64-share-screenshot-capture/before/04-screenshot-live-show-cursor.json b/dogfood/issue-64-share-screenshot-capture/before/04-screenshot-live-show-cursor.json
new file mode 100644
index 0000000..300de33
--- /dev/null
+++ b/dogfood/issue-64-share-screenshot-capture/before/04-screenshot-live-show-cursor.json
@@ -0,0 +1,20 @@
+{
+  "ok": true,
+  "command": "screenshot",
+  "timestamp": "2026-04-30T07:54:25.484Z",
+  "result": {
+    "sessionId": "01KQEP3C9F2CMDX15SQWFTW9MK",
+    "capturedAtSeq": 0,
+    "profileName": "reference-dark",
+    "cols": 80,
+    "rows": 24,
+    "artifactPath": "/tmp/tmp.XjcTHC008g/sessions/01KQEP3C9F2CMDX15SQWFTW9MK/artifacts/screenshot-0-reference-dark.png",
+    "pngSizeBytes": 3790,
+    "cursorVisible": true,
+    "rendererBackend": "ghostty-web",
+    "pixelWidth": 640,
+    "pixelHeight": 384,
+    "sha256": "a658e720e18b2943fd6203e8947a9fe4e60fa0759cb5d0f9c74668abfe267ceb",
+    "renderProfileHash": "8ffed6af301ec7c0e6b69599c3be0d1d12096f9fcdfc59d0bbb4cc474d64c53d"
+  }
+}
diff --git a/dogfood/issue-64-share-screenshot-capture/before/10-create-offline.json b/dogfood/issue-64-share-screenshot-capture/before/10-create-offline.json
new file mode 100644
index 0000000..714bae0
--- /dev/null
+++ b/dogfood/issue-64-share-screenshot-capture/before/10-create-offline.json
@@ -0,0 +1,12 @@
+{
+  "ok": true,
+  "command": "create",
+  "timestamp": "2026-04-30T07:54:27.342Z",
+  "result": {
+    "sessionId": "01KQEP3JANHPG9CKX3X9B2B15K",
+    "createdAt": "2026-04-30T07:54:26.519Z",
+    "cols": 80,
+    "rows": 24,
+    "shell": "/bin/bash"
+  }
+}
diff --git a/dogfood/issue-64-share-screenshot-capture/before/11-wait-offline.json b/dogfood/issue-64-share-screenshot-capture/before/11-wait-offline.json
new file mode 100644
index 0000000..a1f0450
--- /dev/null
+++ b/dogfood/issue-64-share-screenshot-capture/before/11-wait-offline.json
@@ -0,0 +1,9 @@
+{
+  "ok": true,
+  "command": "wait",
+  "timestamp": "2026-04-30T07:54:28.557Z",
+  "result": {
+    "timedOut": false,
+    "exitCode": 0
+  }
+}
diff --git a/dogfood/issue-64-share-screenshot-capture/before/12-screenshot-offline-default.json b/dogfood/issue-64-share-screenshot-capture/before/12-screenshot-offline-default.json
new file mode 100644
index 0000000..cc9204a
--- /dev/null
+++ b/dogfood/issue-64-share-screenshot-capture/before/12-screenshot-offline-default.json
@@ -0,0 +1,20 @@
+{
+  "ok": true,
+  "command": "screenshot",
+  "timestamp": "2026-04-30T07:54:30.111Z",
+  "result": {
+    "sessionId": "01KQEP3JANHPG9CKX3X9B2B15K",
+    "capturedAtSeq": 1,
+    "profileName": "reference-dark",
+    "cols": 80,
+    "rows": 24,
+    "artifactPath": "/tmp/tmp.XjcTHC008g/sessions/01KQEP3JANHPG9CKX3X9B2B15K/artifacts/screenshot-1-reference-dark.png",
+    "pngSizeBytes": 3749,
+    "cursorVisible": false,
+    "rendererBackend": "ghostty-web",
+    "pixelWidth": 640,
+    "pixelHeight": 384,
+    "sha256": "993fb5f9fe5b9ec7ed456b4005ec40478f5ee6bc3c6d5a65f6dbc78fbd60406d",
+    "renderProfileHash": "8ffed6af301ec7c0e6b69599c3be0d1d12096f9fcdfc59d0bbb4cc474d64c53d"
+  }
+}
diff --git a/dogfood/issue-64-share-screenshot-capture/before/13-screenshot-offline-show-cursor.json b/dogfood/issue-64-share-screenshot-capture/before/13-screenshot-offline-show-cursor.json
new file mode 100644
index 0000000..66a5750
--- /dev/null
+++ b/dogfood/issue-64-share-screenshot-capture/before/13-screenshot-offline-show-cursor.json
@@ -0,0 +1,20 @@
+{
+  "ok": true,
+  "command": "screenshot",
+  "timestamp": "2026-04-30T07:54:36.717Z",
+  "result": {
+    "sessionId": "01KQEP3JANHPG9CKX3X9B2B15K",
+    "capturedAtSeq": 1,
+    "profileName": "reference-dark",
+    "cols": 80,
+    "rows": 24,
+    "artifactPath": "/tmp/tmp.XjcTHC008g/sessions/01KQEP3JANHPG9CKX3X9B2B15K/artifacts/screenshot-1-reference-dark.png",
+    "pngSizeBytes": 3749,
+    "cursorVisible": true,
+    "rendererBackend": "ghostty-web",
+    "pixelWidth": 640,
+    "pixelHeight": 384,
+    "sha256": "993fb5f9fe5b9ec7ed456b4005ec40478f5ee6bc3c6d5a65f6dbc78fbd60406d",
+    "renderProfileHash": "8ffed6af301ec7c0e6b69599c3be0d1d12096f9fcdfc59d0bbb4cc474d64c53d"
+  }
+}
diff --git a/dogfood/issue-64-share-screenshot-capture/before/98-destroy-offline.json b/dogfood/issue-64-share-screenshot-capture/before/98-destroy-offline.json
new file mode 100644
index 0000000..51a7681
--- /dev/null
+++ b/dogfood/issue-64-share-screenshot-capture/before/98-destroy-offline.json
@@ -0,0 +1,9 @@
+{
+  "ok": true,
+  "command": "destroy",
+  "timestamp": "2026-04-30T07:54:44.132Z",
+  "result": {
+    "sessionId": "01KQEP3JANHPG9CKX3X9B2B15K",
+    "destroyed": true
+  }
+}
diff --git a/dogfood/issue-64-share-screenshot-capture/before/99-destroy-live.json b/dogfood/issue-64-share-screenshot-capture/before/99-destroy-live.json
new file mode 100644
index 0000000..041174a
--- /dev/null
+++ b/dogfood/issue-64-share-screenshot-capture/before/99-destroy-live.json
@@ -0,0 +1,9 @@
+{
+  "ok": true,
+  "command": "destroy",
+  "timestamp": "2026-04-30T07:54:43.071Z",
+  "result": {
+    "sessionId": "01KQEP3C9F2CMDX15SQWFTW9MK",
+    "destroyed": true
+  }
+}
diff --git a/dogfood/issue-64-share-screenshot-capture/before/agent-tty-home.txt b/dogfood/issue-64-share-screenshot-capture/before/agent-tty-home.txt
new file mode 100644
index 0000000..83ca466
--- /dev/null
+++ b/dogfood/issue-64-share-screenshot-capture/before/agent-tty-home.txt
@@ -0,0 +1 @@
+/tmp/tmp.XjcTHC008g
diff --git a/dogfood/issue-64-share-screenshot-capture/before/live-session-id.txt b/dogfood/issue-64-share-screenshot-capture/before/live-session-id.txt
new file mode 100644
index 0000000..78678c7
--- /dev/null
+++ b/dogfood/issue-64-share-screenshot-capture/before/live-session-id.txt
@@ -0,0 +1 @@
+01KQEP3C9F2CMDX15SQWFTW9MK
diff --git a/dogfood/issue-64-share-screenshot-capture/before/manifest-live.json b/dogfood/issue-64-share-screenshot-capture/before/manifest-live.json
new file mode 100644
index 0000000..eaa18c5
--- /dev/null
+++ b/dogfood/issue-64-share-screenshot-capture/before/manifest-live.json
@@ -0,0 +1,46 @@
+{
+  "version": 1,
+  "sessionId": "01KQEP3C9F2CMDX15SQWFTW9MK",
+  "artifacts": [
+    {
+      "id": "01KQEP3FYJCBS7P29WTCM3BCNQ",
+      "kind": "screenshot",
+      "filename": "screenshot-0-reference-dark.png",
+      "sessionId": "01KQEP3C9F2CMDX15SQWFTW9MK",
+      "capturedAtSeq": 0,
+      "createdAt": "2026-04-30T07:54:24.082Z",
+      "sha256": "a658e720e18b2943fd6203e8947a9fe4e60fa0759cb5d0f9c74668abfe267ceb",
+      "metadata": {
+        "profileName": "reference-dark",
+        "cols": 80,
+        "rows": 24,
+        "pngSizeBytes": 3790,
+        "cursorVisible": false,
+        "rendererBackend": "ghostty-web",
+        "pixelWidth": 640,
+        "pixelHeight": 384,
+        "renderProfileHash": "8ffed6af301ec7c0e6b69599c3be0d1d12096f9fcdfc59d0bbb4cc474d64c53d"
+      }
+    },
+    {
+      "id": "01KQEP3HA9GE8KJW8CYQMBEDC1",
+      "kind": "screenshot",
+      "filename": "screenshot-0-reference-dark.png",
+      "sessionId": "01KQEP3C9F2CMDX15SQWFTW9MK",
+      "capturedAtSeq": 0,
+      "createdAt": "2026-04-30T07:54:25.481Z",
+      "sha256": "a658e720e18b2943fd6203e8947a9fe4e60fa0759cb5d0f9c74668abfe267ceb",
+      "metadata": {
+        "profileName": "reference-dark",
+        "cols": 80,
+        "rows": 24,
+        "pngSizeBytes": 3790,
+        "cursorVisible": true,
+        "rendererBackend": "ghostty-web",
+        "pixelWidth": 640,
+        "pixelHeight": 384,
+        "renderProfileHash": "8ffed6af301ec7c0e6b69599c3be0d1d12096f9fcdfc59d0bbb4cc474d64c53d"
+      }
+    }
+  ]
+}
diff --git a/dogfood/issue-64-share-screenshot-capture/before/manifest-offline.json b/dogfood/issue-64-share-screenshot-capture/before/manifest-offline.json
new file mode 100644
index 0000000..f250b71
--- /dev/null
+++ b/dogfood/issue-64-share-screenshot-capture/before/manifest-offline.json
@@ -0,0 +1,46 @@
+{
+  "version": 1,
+  "sessionId": "01KQEP3JANHPG9CKX3X9B2B15K",
+  "artifacts": [
+    {
+      "id": "01KQEP3NSKDDYAV1QXM953RNMH",
+      "kind": "screenshot",
+      "filename": "screenshot-1-reference-dark.png",
+      "sessionId": "01KQEP3JANHPG9CKX3X9B2B15K",
+      "capturedAtSeq": 1,
+      "createdAt": "2026-04-30T07:54:30.067Z",
+      "sha256": "993fb5f9fe5b9ec7ed456b4005ec40478f5ee6bc3c6d5a65f6dbc78fbd60406d",
+      "metadata": {
+        "profileName": "reference-dark",
+        "cols": 80,
+        "rows": 24,
+        "pngSizeBytes": 3749,
+        "cursorVisible": false,
+        "rendererBackend": "ghostty-web",
+        "pixelWidth": 640,
+        "pixelHeight": 384,
+        "renderProfileHash": "8ffed6af301ec7c0e6b69599c3be0d1d12096f9fcdfc59d0bbb4cc474d64c53d"
+      }
+    },
+    {
+      "id": "01KQEP3W85YF3P43GJCXNZPKC3",
+      "kind": "screenshot",
+      "filename": "screenshot-1-reference-dark.png",
+      "sessionId": "01KQEP3JANHPG9CKX3X9B2B15K",
+      "capturedAtSeq": 1,
+      "createdAt": "2026-04-30T07:54:36.677Z",
+      "sha256": "993fb5f9fe5b9ec7ed456b4005ec40478f5ee6bc3c6d5a65f6dbc78fbd60406d",
+      "metadata": {
+        "profileName": "reference-dark",
+        "cols": 80,
+        "rows": 24,
+        "pngSizeBytes": 3749,
+        "cursorVisible": true,
+        "rendererBackend": "ghostty-web",
+        "pixelWidth": 640,
+        "pixelHeight": 384,
+        "renderProfileHash": "8ffed6af301ec7c0e6b69599c3be0d1d12096f9fcdfc59d0bbb4cc474d64c53d"
+      }
+    }
+  ]
+}
diff --git a/dogfood/issue-64-share-screenshot-capture/before/offline-session-id.txt b/dogfood/issue-64-share-screenshot-capture/before/offline-session-id.txt
new file mode 100644
index 0000000..f89499d
--- /dev/null
+++ b/dogfood/issue-64-share-screenshot-capture/before/offline-session-id.txt
@@ -0,0 +1 @@
+01KQEP3JANHPG9CKX3X9B2B15K
diff --git a/dogfood/issue-64-share-screenshot-capture/before/screenshot-live-default.png b/dogfood/issue-64-share-screenshot-capture/before/screenshot-live-default.png
new file mode 100644
index 0000000..376bebc
Binary files /dev/null and b/dogfood/issue-64-share-screenshot-capture/before/screenshot-live-default.png differ
diff --git a/dogfood/issue-64-share-screenshot-capture/before/screenshot-live-show-cursor.png b/dogfood/issue-64-share-screenshot-capture/before/screenshot-live-show-cursor.png
new file mode 100644
index 0000000..376bebc
Binary files /dev/null and b/dogfood/issue-64-share-screenshot-capture/before/screenshot-live-show-cursor.png differ
diff --git a/dogfood/issue-64-share-screenshot-capture/before/screenshot-offline-default.png b/dogfood/issue-64-share-screenshot-capture/before/screenshot-offline-default.png
new file mode 100644
index 0000000..2f9738b
Binary files /dev/null and b/dogfood/issue-64-share-screenshot-capture/before/screenshot-offline-default.png differ
diff --git a/dogfood/issue-64-share-screenshot-capture/before/screenshot-offline-show-cursor.png b/dogfood/issue-64-share-screenshot-capture/before/screenshot-offline-show-cursor.png
new file mode 100644
index 0000000..2f9738b
Binary files /dev/null and b/dogfood/issue-64-share-screenshot-capture/before/screenshot-offline-show-cursor.png differ
diff --git a/dogfood/issue-64-share-screenshot-capture/before/sha256-summary.txt b/dogfood/issue-64-share-screenshot-capture/before/sha256-summary.txt
new file mode 100644
index 0000000..3737de7
--- /dev/null
+++ b/dogfood/issue-64-share-screenshot-capture/before/sha256-summary.txt
@@ -0,0 +1,8 @@
+screenshot-live-default.png:
+a658e720e18b2943fd6203e8947a9fe4e60fa0759cb5d0f9c74668abfe267ceb
+screenshot-live-show-cursor.png:
+a658e720e18b2943fd6203e8947a9fe4e60fa0759cb5d0f9c74668abfe267ceb
+screenshot-offline-default.png:
+993fb5f9fe5b9ec7ed456b4005ec40478f5ee6bc3c6d5a65f6dbc78fbd60406d
+screenshot-offline-show-cursor.png:
+993fb5f9fe5b9ec7ed456b4005ec40478f5ee6bc3c6d5a65f6dbc78fbd60406d
diff --git a/dogfood/issue-64-share-screenshot-capture/before/transcript.txt b/dogfood/issue-64-share-screenshot-capture/before/transcript.txt
new file mode 100644
index 0000000..2e2f361
--- /dev/null
+++ b/dogfood/issue-64-share-screenshot-capture/before/transcript.txt
@@ -0,0 +1,152 @@
+Running with label: before
+Repo HEAD: b2d506802110a97ebd4cc8b985970a19211fd36b
++ npx tsx src/cli/main.ts create --json --name issue-64-live -- /bin/sh -c printf\ \"live\ screenshot\ fixture\\n\"\;\ sleep\ 60
+{
+  "ok": true,
+  "command": "create",
+  "timestamp": "2026-04-30T07:54:21.162Z",
+  "result": {
+    "sessionId": "01KQEP3C9F2CMDX15SQWFTW9MK",
+    "createdAt": "2026-04-30T07:54:20.338Z",
+    "cols": 80,
+    "rows": 24,
+    "shell": "/bin/bash"
+  }
+}
+
++ npx tsx src/cli/main.ts wait 01KQEP3C9F2CMDX15SQWFTW9MK --text live\ screenshot\ fixture --timeout 5000 --json
+{
+  "ok": true,
+  "command": "wait",
+  "timestamp": "2026-04-30T07:54:22.828Z",
+  "result": {
+    "matched": true,
+    "timedOut": false,
+    "matchedText": "live screenshot fixture",
+    "cursorRow": 1,
+    "cursorCol": 0,
+    "capturedAtSeq": 0
+  }
+}
+
++ npx tsx src/cli/main.ts screenshot 01KQEP3C9F2CMDX15SQWFTW9MK --json
+{
+  "ok": true,
+  "command": "screenshot",
+  "timestamp": "2026-04-30T07:54:24.088Z",
+  "result": {
+    "sessionId": "01KQEP3C9F2CMDX15SQWFTW9MK",
+    "capturedAtSeq": 0,
+    "profileName": "reference-dark",
+    "cols": 80,
+    "rows": 24,
+    "artifactPath": "/tmp/tmp.XjcTHC008g/sessions/01KQEP3C9F2CMDX15SQWFTW9MK/artifacts/screenshot-0-reference-dark.png",
+    "pngSizeBytes": 3790,
+    "cursorVisible": false,
+    "rendererBackend": "ghostty-web",
+    "pixelWidth": 640,
+    "pixelHeight": 384,
+    "sha256": "a658e720e18b2943fd6203e8947a9fe4e60fa0759cb5d0f9c74668abfe267ceb",
+    "renderProfileHash": "8ffed6af301ec7c0e6b69599c3be0d1d12096f9fcdfc59d0bbb4cc474d64c53d"
+  }
+}
+
++ npx tsx src/cli/main.ts screenshot 01KQEP3C9F2CMDX15SQWFTW9MK --show-cursor --json
+{
+  "ok": true,
+  "command": "screenshot",
+  "timestamp": "2026-04-30T07:54:25.484Z",
+  "result": {
+    "sessionId": "01KQEP3C9F2CMDX15SQWFTW9MK",
+    "capturedAtSeq": 0,
+    "profileName": "reference-dark",
+    "cols": 80,
+    "rows": 24,
+    "artifactPath": "/tmp/tmp.XjcTHC008g/sessions/01KQEP3C9F2CMDX15SQWFTW9MK/artifacts/screenshot-0-reference-dark.png",
+    "pngSizeBytes": 3790,
+    "cursorVisible": true,
+    "rendererBackend": "ghostty-web",
+    "pixelWidth": 640,
+    "pixelHeight": 384,
+    "sha256": "a658e720e18b2943fd6203e8947a9fe4e60fa0759cb5d0f9c74668abfe267ceb",
+    "renderProfileHash": "8ffed6af301ec7c0e6b69599c3be0d1d12096f9fcdfc59d0bbb4cc474d64c53d"
+  }
+}
+
++ npx tsx src/cli/main.ts create --json --name issue-64-offline -- /bin/sh -c printf\ \"offline\ screenshot\ fixture\\n\"
+{
+  "ok": true,
+  "command": "create",
+  "timestamp": "2026-04-30T07:54:27.342Z",
+  "result": {
+    "sessionId": "01KQEP3JANHPG9CKX3X9B2B15K",
+    "createdAt": "2026-04-30T07:54:26.519Z",
+    "cols": 80,
+    "rows": 24,
+    "shell": "/bin/bash"
+  }
+}
+
++ npx tsx src/cli/main.ts wait 01KQEP3JANHPG9CKX3X9B2B15K --exit --timeout 10000 --json
+{
+  "ok": true,
+  "command": "wait",
+  "timestamp": "2026-04-30T07:54:28.557Z",
+  "result": {
+    "timedOut": false,
+    "exitCode": 0
+  }
+}
+
++ npx tsx src/cli/main.ts screenshot 01KQEP3JANHPG9CKX3X9B2B15K --json
+{
+  "ok": true,
+  "command": "screenshot",
+  "timestamp": "2026-04-30T07:54:30.111Z",
+  "result": {
+    "sessionId": "01KQEP3JANHPG9CKX3X9B2B15K",
+    "capturedAtSeq": 1,
+    "profileName": "reference-dark",
+    "cols": 80,
+    "rows": 24,
+    "artifactPath": "/tmp/tmp.XjcTHC008g/sessions/01KQEP3JANHPG9CKX3X9B2B15K/artifacts/screenshot-1-reference-dark.png",
+    "pngSizeBytes": 3749,
+    "cursorVisible": false,
+    "rendererBackend": "ghostty-web",
+    "pixelWidth": 640,
+    "pixelHeight": 384,
+    "sha256": "993fb5f9fe5b9ec7ed456b4005ec40478f5ee6bc3c6d5a65f6dbc78fbd60406d",
+    "renderProfileHash": "8ffed6af301ec7c0e6b69599c3be0d1d12096f9fcdfc59d0bbb4cc474d64c53d"
+  }
+}
+
++ npx tsx src/cli/main.ts screenshot 01KQEP3JANHPG9CKX3X9B2B15K --show-cursor --json
+{
+  "ok": true,
+  "command": "screenshot",
+  "timestamp": "2026-04-30T07:54:36.717Z",
+  "result": {
+    "sessionId": "01KQEP3JANHPG9CKX3X9B2B15K",
+    "capturedAtSeq": 1,
+    "profileName": "reference-dark",
+    "cols": 80,
+    "rows": 24,
+    "artifactPath": "/tmp/tmp.XjcTHC008g/sessions/01KQEP3JANHPG9CKX3X9B2B15K/artifacts/screenshot-1-reference-dark.png",
+    "pngSizeBytes": 3749,
+    "cursorVisible": true,
+    "rendererBackend": "ghostty-web",
+    "pixelWidth": 640,
+    "pixelHeight": 384,
+    "sha256": "993fb5f9fe5b9ec7ed456b4005ec40478f5ee6bc3c6d5a65f6dbc78fbd60406d",
+    "renderProfileHash": "8ffed6af301ec7c0e6b69599c3be0d1d12096f9fcdfc59d0bbb4cc474d64c53d"
+  }
+}
+
+screenshot-live-default.png:
+a658e720e18b2943fd6203e8947a9fe4e60fa0759cb5d0f9c74668abfe267ceb
+screenshot-live-show-cursor.png:
+a658e720e18b2943fd6203e8947a9fe4e60fa0759cb5d0f9c74668abfe267ceb
+screenshot-offline-default.png:
+993fb5f9fe5b9ec7ed456b4005ec40478f5ee6bc3c6d5a65f6dbc78fbd60406d
+screenshot-offline-show-cursor.png:
+993fb5f9fe5b9ec7ed456b4005ec40478f5ee6bc3c6d5a65f6dbc78fbd60406d
diff --git a/dogfood/issue-64-share-screenshot-capture/commands.sh b/dogfood/issue-64-share-screenshot-capture/commands.sh
new file mode 100755
index 0000000..142f1f5
--- /dev/null
+++ b/dogfood/issue-64-share-screenshot-capture/commands.sh
@@ -0,0 +1,127 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+# Issue 64: Share screenshot capture and artifact persistence.
+#
+# This script captures four screenshot scenarios:
+#
+# 1. Live (running session) screenshot, default cursor.
+# 2. Live (running session) screenshot, --show-cursor.
+# 3. Offline (destroyed session) screenshot, default cursor.
+# 4. Offline (destroyed session) screenshot, --show-cursor.
+#
+# It records each screenshot's JSON envelope, the captured PNG, and the
+# session's artifact manifest entry so a reviewer can compare the live and
+# offline paths field-by-field. Run twice — once on the refactor branch and
+# once on the parent commit — to compare before/after parity:
+#
+#   bash dogfood/issue-64-share-screenshot-capture/commands.sh after
+#   bash dogfood/issue-64-share-screenshot-capture/commands.sh before
+#
+# Each invocation writes to the corresponding sub-directory under the bundle
+# (`after/` or `before/`). The label argument defaults to `after` if omitted.
+
+BUNDLE="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+REPO="$(cd "$BUNDLE/../.." && pwd)"
+LABEL="${1:-after}"
+OUT="$BUNDLE/$LABEL"
+mkdir -p "$OUT"
+
+export AGENT_TTY_HOME="$(mktemp -d)"
+printf '%s\n' "$AGENT_TTY_HOME" > "$OUT/agent-tty-home.txt"
+
+cd "$REPO"
+exec > >(tee "$OUT/transcript.txt") 2>&1
+printf 'Running with label: %s\nRepo HEAD: %s\n' "$LABEL" "$(git rev-parse HEAD)"
+
+run_json() {
+  local output="$1"
+  shift
+  printf '+'
+  for argument in "$@"; do
+    printf ' %q' "$argument"
+  done
+  printf '\n'
+  "$@" > "$output"
+  cat "$output"
+  printf '\n'
+}
+
+json_field() {
+  local file="$1"
+  local expression="$2"
+  node -e "const fs = require('node:fs'); const envelope = JSON.parse(fs.readFileSync(process.argv[1], 'utf8')); console.log($expression);" "$file"
+}
+
+cleanup() {
+  if [[ -n "${LIVE_SESSION_ID:-}" ]]; then
+    npx tsx src/cli/main.ts destroy "$LIVE_SESSION_ID" --json > "$OUT/99-destroy-live.json" || true
+  fi
+  if [[ -n "${OFFLINE_SESSION_ID:-}" ]]; then
+    npx tsx src/cli/main.ts destroy "$OFFLINE_SESSION_ID" --json > "$OUT/98-destroy-offline.json" || true
+  fi
+  if [[ -n "${AGENT_TTY_HOME:-}" ]]; then
+    rm -rf "$AGENT_TTY_HOME"
+  fi
+}
+trap cleanup EXIT
+
+# --- Live session: capture screenshots while it is still running. ---
+run_json "$OUT/01-create-live.json" \
+  npx tsx src/cli/main.ts create --json --name issue-64-live -- /bin/sh -c 'printf "live screenshot fixture\n"; sleep 60'
+LIVE_SESSION_ID="$(json_field "$OUT/01-create-live.json" 'envelope.result.sessionId')"
+printf '%s\n' "$LIVE_SESSION_ID" > "$OUT/live-session-id.txt"
+
+# Wait for the prompt to settle so the rendered output is deterministic.
+run_json "$OUT/02-wait-live.json" \
+  npx tsx src/cli/main.ts wait "$LIVE_SESSION_ID" --text 'live screenshot fixture' --timeout 5000 --json
+
+run_json "$OUT/03-screenshot-live-default.json" \
+  npx tsx src/cli/main.ts screenshot "$LIVE_SESSION_ID" --json
+LIVE_DEFAULT_PATH="$(json_field "$OUT/03-screenshot-live-default.json" 'envelope.result.artifactPath')"
+cp "$LIVE_DEFAULT_PATH" "$OUT/screenshot-live-default.png"
+
+run_json "$OUT/04-screenshot-live-show-cursor.json" \
+  npx tsx src/cli/main.ts screenshot "$LIVE_SESSION_ID" --show-cursor --json
+LIVE_CURSOR_PATH="$(json_field "$OUT/04-screenshot-live-show-cursor.json" 'envelope.result.artifactPath')"
+cp "$LIVE_CURSOR_PATH" "$OUT/screenshot-live-show-cursor.png"
+
+LIVE_SESSION_DIR="$AGENT_TTY_HOME/sessions/$LIVE_SESSION_ID"
+cp "$LIVE_SESSION_DIR/artifacts/manifest.json" "$OUT/manifest-live.json"
+
+# --- Offline session: capture screenshots after the session has exited. ---
+run_json "$OUT/10-create-offline.json" \
+  npx tsx src/cli/main.ts create --json --name issue-64-offline -- /bin/sh -c 'printf "offline screenshot fixture\n"'
+OFFLINE_SESSION_ID="$(json_field "$OUT/10-create-offline.json" 'envelope.result.sessionId')"
+printf '%s\n' "$OFFLINE_SESSION_ID" > "$OUT/offline-session-id.txt"
+
+# Wait for the short-lived session to exit so subsequent screenshot RPCs
+# fall through to the offline replay path.
+run_json "$OUT/11-wait-offline.json" \
+  npx tsx src/cli/main.ts wait "$OFFLINE_SESSION_ID" --exit --timeout 10000 --json
+
+run_json "$OUT/12-screenshot-offline-default.json" \
+  npx tsx src/cli/main.ts screenshot "$OFFLINE_SESSION_ID" --json
+OFFLINE_DEFAULT_PATH="$(json_field "$OUT/12-screenshot-offline-default.json" 'envelope.result.artifactPath')"
+cp "$OFFLINE_DEFAULT_PATH" "$OUT/screenshot-offline-default.png"
+
+run_json "$OUT/13-screenshot-offline-show-cursor.json" \
+  npx tsx src/cli/main.ts screenshot "$OFFLINE_SESSION_ID" --show-cursor --json
+OFFLINE_CURSOR_PATH="$(json_field "$OUT/13-screenshot-offline-show-cursor.json" 'envelope.result.artifactPath')"
+cp "$OFFLINE_CURSOR_PATH" "$OUT/screenshot-offline-show-cursor.png"
+
+OFFLINE_SESSION_DIR="$AGENT_TTY_HOME/sessions/$OFFLINE_SESSION_ID"
+cp "$OFFLINE_SESSION_DIR/artifacts/manifest.json" "$OUT/manifest-offline.json"
+
+# Record SHA-256 sums for quick visual diffing across before/after runs.
+{
+  printf 'screenshot-live-default.png:\n'
+  json_field "$OUT/03-screenshot-live-default.json" 'envelope.result.sha256'
+  printf 'screenshot-live-show-cursor.png:\n'
+  json_field "$OUT/04-screenshot-live-show-cursor.json" 'envelope.result.sha256'
+  printf 'screenshot-offline-default.png:\n'
+  json_field "$OUT/12-screenshot-offline-default.json" 'envelope.result.sha256'
+  printf 'screenshot-offline-show-cursor.png:\n'
+  json_field "$OUT/13-screenshot-offline-show-cursor.json" 'envelope.result.sha256'
+} > "$OUT/sha256-summary.txt"
+cat "$OUT/sha256-summary.txt"
diff --git a/src/cli/commands/screenshot.ts b/src/cli/commands/screenshot.ts
index 0e9f2fe..691b4f4 100644
--- a/src/cli/commands/screenshot.ts
+++ b/src/cli/commands/screenshot.ts
@@ -1,7 +1,3 @@
-import { rename, rm } from 'node:fs/promises';
-
-import { ulid } from 'ulid';
-
 import type { ScreenshotResult } from '../../protocol/messages.js';
 
 import type { CommandContext } from '../context.js';
@@ -10,25 +6,18 @@ import { emitSuccess } from '../output.js';
 import { CliError } from '../../cli/errors.js';
 import { sendRpc } from '../../host/rpcClient.js';
 import { ScreenshotParamsSchema } from '../../protocol/messages.js';
-import { ScreenshotResultSchema } from '../../protocol/schemas.js';
 import { ERROR_CODES, makeCliError } from '../../protocol/errors.js';
 import { withOfflineReplayRenderer } from '../../replay/offlineReplay.js';
 import {
-  appendArtifact,
-  createArtifactEntry,
-} from '../../storage/artifactManifest.js';
-import {
-  artifactPath,
-  ensureArtifactsDir,
-  screenshotFilename,
-} from '../../storage/artifactPaths.js';
+  captureScreenshotResult,
+  parseScreenshotResult,
+} from '../../screenshot/capture.js';
 import { readManifestIfExists } from '../../storage/manifests.js';
 import {
   manifestPath,
   sessionDir,
   socketPath,
 } from '../../storage/sessionPaths.js';
-import { invariant } from '../../util/assert.js';
 
 const DEFAULT_SCREENSHOT_PROFILE = 'reference-dark';
 
@@ -113,21 +102,6 @@ function formatScreenshotLines(result: ScreenshotResult): string[] {
   return lines;
 }
 
-function parseScreenshotResult(
-  rawResult: unknown,
-  invalidResultMessage: string,
-): ScreenshotResult {
-  const parsedResult = ScreenshotResultSchema.safeParse(rawResult);
-  if (!parsedResult.success) {
-    throw makeCliError(ERROR_CODES.PROTOCOL_ERROR, {
-      message: invalidResultMessage,
-      details: { issues: parsedResult.error.issues },
-    });
-  }
-
-  return parsedResult.data;
-}
-
 async function runOfflineScreenshot(
   sessionDirectory: string,
   rendererName: CommandContext['rendererDefault'],
@@ -136,83 +110,14 @@ async function runOfflineScreenshot(
 ): Promise<ScreenshotResult> {
   return withOfflineReplayRenderer(
     { sessionDir: sessionDirectory, profileName: profile, rendererName },
-    async ({ backend, manifest }) => {
-      await ensureArtifactsDir(sessionDirectory);
-      const temporaryOutputPath = artifactPath(
-        sessionDirectory,
-        `.tmp-screenshot-${ulid()}.png`,
-      );
-
-      try {
-        const result = await backend.screenshot(
-          temporaryOutputPath,
-          showCursor === undefined ? undefined : { showCursor },
-        );
-        invariant(
-          result.sessionId === manifest.sessionId,
-          'offline screenshot sessionId must match the manifest sessionId',
-        );
-        invariant(
-          result.profileName === profile,
-          'offline screenshot profileName must match the requested profile',
-        );
-        invariant(
-          result.pngSizeBytes > 0,
-          'offline screenshot pngSizeBytes must be positive',
-        );
-        invariant(
-          result.sha256 !== undefined,
-          'offline screenshot must produce sha256',
-        );
-
-        const filename = screenshotFilename(
-          result.capturedAtSeq,
-          result.profileName,
-        );
-        const finalArtifactPath = artifactPath(sessionDirectory, filename);
-        await rename(temporaryOutputPath, finalArtifactPath);
-        await appendArtifact(
-          sessionDirectory,
-          createArtifactEntry({
-            kind: 'screenshot',
-            filename,
-            sessionId: result.sessionId,
-            capturedAtSeq: result.capturedAtSeq,
-            sha256: result.sha256,
-            metadata: {
-              profileName: result.profileName,
-              cols: result.cols,
-              rows: result.rows,
-              pngSizeBytes: result.pngSizeBytes,
-              cursorVisible: result.cursorVisible,
-              rendererBackend: result.rendererBackend,
-              pixelWidth: result.pixelWidth,
-              pixelHeight: result.pixelHeight,
-              renderProfileHash: result.renderProfileHash,
-            },
-          }),
-        );
-
-        return {
-          sessionId: result.sessionId,
-          capturedAtSeq: result.capturedAtSeq,
-          profileName: result.profileName,
-          cols: result.cols,
-          rows: result.rows,
-          artifactPath: finalArtifactPath,
-          pngSizeBytes: result.pngSizeBytes,
-          cursorVisible: result.cursorVisible,
-          rendererBackend: result.rendererBackend,
-          pixelWidth: result.pixelWidth,
-          pixelHeight: result.pixelHeight,
-          sha256: result.sha256,
-          renderProfileHash: result.renderProfileHash,
-        };
-      } catch (error) {
-        await rm(temporaryOutputPath, { force: true }).catch(() => undefined);
-        throw error;
-      }
-    },
+    async ({ backend, manifest }) =>
+      captureScreenshotResult({
+        backend,
+        sessionDir: sessionDirectory,
+        profileName: profile,
+        expectedSessionId: manifest.sessionId,
+        ...(showCursor === undefined ? {} : { showCursor }),
+      }),
   );
 }
 
@@ -252,19 +157,26 @@ export async function runScreenshotCommand(
     });
   }
 
-  let rawResult: unknown;
-  let invalidResultMessage = 'Unexpected response from host';
+  let result: ScreenshotResult;
 
   // Snapshot and screenshot intentionally keep their narrower legacy live-RPC
   // gate. `exiting` sessions are live-host eligible for inspect, but these
   // commands preserve their existing offline-replay capture behavior.
   if (manifest.status === 'running') {
     try {
-      rawResult = await sendRpc(socketPath(sessionDirectory), 'screenshot', {
-        profile,
-        rendererName: options.context.rendererDefault,
-        ...(showCursor === undefined ? {} : { showCursor }),
-      });
+      const rawResult = await sendRpc(
+        socketPath(sessionDirectory),
+        'screenshot',
+        {
+          profile,
+          rendererName: options.context.rendererDefault,
+          ...(showCursor === undefined ? {} : { showCursor }),
+        },
+      );
+      result = parseScreenshotResult(
+        rawResult,
+        'Unexpected response from host',
+      );
     } catch (error) {
       if (
         !(error instanceof CliError) ||
@@ -273,26 +185,22 @@ export async function runScreenshotCommand(
         throw error;
       }
 
-      rawResult = await runOfflineScreenshot(
+      result = await runOfflineScreenshot(
         sessionDirectory,
         options.context.rendererDefault,
         profile,
         showCursor,
       );
-      invalidResultMessage = 'Unexpected screenshot result from offline replay';
     }
   } else {
-    rawResult = await runOfflineScreenshot(
+    result = await runOfflineScreenshot(
       sessionDirectory,
       options.context.rendererDefault,
       profile,
       showCursor,
     );
-    invalidResultMessage = 'Unexpected screenshot result from offline replay';
   }
 
-  const result = parseScreenshotResult(rawResult, invalidResultMessage);
-
   emitSuccess({
     command: 'screenshot',
     json: options.json,
diff --git a/src/host/hostMain.ts b/src/host/hostMain.ts
index 84f1414..25ea8f8 100644
--- a/src/host/hostMain.ts
+++ b/src/host/hostMain.ts
@@ -1,9 +1,7 @@
-import { mkdir, rename, rm } from 'node:fs/promises';
+import { mkdir } from 'node:fs/promises';
 import { dirname } from 'node:path';
 import process from 'node:process';
 
-import { ulid } from 'ulid';
-
 import {
   matchRenderWaitSnapshot,
   prepareRenderWaitCondition,
@@ -41,16 +39,8 @@ import {
 } from '../renderer/names.js';
 import { resolveProfile } from '../renderer/profiles.js';
 import { createRendererBackend } from '../renderer/registry.js';
+import { captureScreenshotResult } from '../screenshot/capture.js';
 import { captureSnapshotResult } from '../snapshot/capture.js';
-import {
-  appendArtifact,
-  createArtifactEntry,
-} from '../storage/artifactManifest.js';
-import {
-  artifactPath,
-  ensureArtifactsDir,
-  screenshotFilename,
-} from '../storage/artifactPaths.js';
 import { resolveHome } from '../storage/home.js';
 import { readManifest, writeManifest } from '../storage/manifests.js';
 import {
@@ -436,83 +426,14 @@ export async function runHost(sessionId: string): Promise<void> {
         profile,
         replayInput,
       );
-      await ensureArtifactsDir(sessDir);
-      const temporaryOutputPath = artifactPath(
-        sessDir,
-        `.tmp-screenshot-${ulid()}.png`,
-      );
-
-      try {
-        const result = await backend.screenshot(
-          temporaryOutputPath,
-          showCursor === undefined ? undefined : { showCursor },
-        );
-
-        invariant(
-          result.sessionId === sessionId,
-          'renderer screenshot sessionId must match host sessionId',
-        );
-        invariant(
-          result.profileName === profile.name,
-          'renderer screenshot profileName must match the requested profile',
-        );
-        invariant(
-          result.artifactPath === temporaryOutputPath,
-          'renderer screenshot path must match the requested output path',
-        );
-        invariant(
-          result.pngSizeBytes > 0,
-          'renderer screenshot pngSizeBytes must be positive',
-        );
 
-        const filename = screenshotFilename(
-          result.capturedAtSeq,
-          result.profileName,
-        );
-        const finalArtifactPath = artifactPath(sessDir, filename);
-
-        await rename(temporaryOutputPath, finalArtifactPath);
-        await appendArtifact(
-          sessDir,
-          createArtifactEntry({
-            kind: 'screenshot',
-            filename,
-            sessionId: result.sessionId,
-            capturedAtSeq: result.capturedAtSeq,
-            sha256: result.sha256,
-            metadata: {
-              profileName: result.profileName,
-              cols: result.cols,
-              rows: result.rows,
-              pngSizeBytes: result.pngSizeBytes,
-              cursorVisible: result.cursorVisible,
-              rendererBackend: result.rendererBackend,
-              pixelWidth: result.pixelWidth,
-              pixelHeight: result.pixelHeight,
-              renderProfileHash: result.renderProfileHash,
-            },
-          }),
-        );
-
-        return {
-          sessionId: result.sessionId,
-          capturedAtSeq: result.capturedAtSeq,
-          profileName: result.profileName,
-          cols: result.cols,
-          rows: result.rows,
-          artifactPath: finalArtifactPath,
-          pngSizeBytes: result.pngSizeBytes,
-          cursorVisible: result.cursorVisible,
-          rendererBackend: result.rendererBackend,
-          pixelWidth: result.pixelWidth,
-          pixelHeight: result.pixelHeight,
-          sha256: result.sha256,
-          renderProfileHash: result.renderProfileHash,
-        };
-      } catch (error) {
-        await rm(temporaryOutputPath, { force: true }).catch(() => undefined);
-        throw error;
-      }
+      return await captureScreenshotResult({
+        backend,
+        sessionDir: sessDir,
+        profileName: profile.name,
+        expectedSessionId: sessionId,
+        ...(showCursor === undefined ? {} : { showCursor }),
+      });
     },
     type: async (params: unknown) => {
       const { text } = params as TypeParams;
diff --git a/src/screenshot/capture.ts b/src/screenshot/capture.ts
new file mode 100644
index 0000000..84d3282
--- /dev/null
+++ b/src/screenshot/capture.ts
@@ -0,0 +1,172 @@
+import { rename, rm } from 'node:fs/promises';
+
+import { ulid } from 'ulid';
+
+import type { ScreenshotResult } from '../protocol/messages.js';
+import type { RendererBackend } from '../renderer/backend.js';
+
+import { ERROR_CODES, makeCliError } from '../protocol/errors.js';
+import { ScreenshotResultSchema } from '../protocol/schemas.js';
+import {
+  appendArtifact,
+  createArtifactEntry,
+} from '../storage/artifactManifest.js';
+import {
+  artifactPath,
+  ensureArtifactsDir,
+  screenshotFilename,
+} from '../storage/artifactPaths.js';
+import { invariant } from '../util/assert.js';
+
+/**
+ * The narrow renderer surface the capture helper needs. Accepting only
+ * `screenshot()` makes it impossible for future edits to reach for unrelated
+ * lifecycle methods (`boot`, `replayTo`, `dispose`, etc.) from inside the
+ * capture seam. Callers already hold a full `RendererBackend`, which is
+ * structurally assignable to this `Pick<...>`.
+ */
+export type CaptureScreenshotBackend = Pick<RendererBackend, 'screenshot'>;
+
+/**
+ * The shared capture path enforces `sha256` as a runtime invariant on every
+ * successful screenshot. We refine the public schema's optional `sha256` to
+ * `string` here so callers — and TypeScript — see that guarantee directly.
+ */
+export type CapturedScreenshotResult = ScreenshotResult & { sha256: string };
+
+export interface CaptureScreenshotResultOptions {
+  backend: CaptureScreenshotBackend;
+  sessionDir: string;
+  profileName: string;
+  expectedSessionId: string;
+  showCursor?: boolean;
+}
+
+export function parseScreenshotResult(
+  rawResult: unknown,
+  message = 'Unexpected response from host',
+): ScreenshotResult {
+  const parsedResult = ScreenshotResultSchema.safeParse(rawResult);
+  if (!parsedResult.success) {
+    throw makeCliError(ERROR_CODES.PROTOCOL_ERROR, {
+      message,
+      details: { issues: parsedResult.error.issues },
+    });
+  }
+
+  return parsedResult.data;
+}
+
+export async function captureScreenshotResult(
+  options: CaptureScreenshotResultOptions,
+): Promise<CapturedScreenshotResult> {
+  invariant(options.sessionDir.length > 0, 'sessionDir must be non-empty');
+  invariant(options.profileName.length > 0, 'profileName must be non-empty');
+  invariant(
+    options.expectedSessionId.length > 0,
+    'expectedSessionId must be non-empty',
+  );
+
+  await ensureArtifactsDir(options.sessionDir);
+  const temporaryOutputPath = artifactPath(
+    options.sessionDir,
+    `.tmp-screenshot-${ulid()}.png`,
+  );
+
+  try {
+    const rendererResult = await options.backend.screenshot(
+      temporaryOutputPath,
+      options.showCursor === undefined
+        ? undefined
+        : { showCursor: options.showCursor },
+    );
+
+    invariant(
+      rendererResult.sessionId === options.expectedSessionId,
+      'renderer screenshot sessionId must match expected sessionId',
+    );
+    invariant(
+      rendererResult.profileName === options.profileName,
+      'renderer screenshot profileName must match the requested profile',
+    );
+    invariant(
+      rendererResult.pngSizeBytes > 0,
+      'renderer screenshot pngSizeBytes must be positive',
+    );
+    invariant(
+      rendererResult.artifactPath === temporaryOutputPath,
+      'renderer screenshot path must match the requested output path',
+    );
+    const sha256 = rendererResult.sha256;
+    invariant(sha256 !== undefined, 'renderer screenshot must produce sha256');
+
+    const filename = screenshotFilename(
+      rendererResult.capturedAtSeq,
+      rendererResult.profileName,
+    );
+    const finalArtifactPath = artifactPath(options.sessionDir, filename);
+
+    // Mirror `src/snapshot/capture.ts` by building a typed intermediate
+    // before validation. A misspelled field name surfaces at compile time
+    // here rather than only at Zod runtime.
+    const publicResultCandidate: CapturedScreenshotResult = {
+      sessionId: rendererResult.sessionId,
+      capturedAtSeq: rendererResult.capturedAtSeq,
+      profileName: rendererResult.profileName,
+      cols: rendererResult.cols,
+      rows: rendererResult.rows,
+      artifactPath: finalArtifactPath,
+      pngSizeBytes: rendererResult.pngSizeBytes,
+      cursorVisible: rendererResult.cursorVisible,
+      rendererBackend: rendererResult.rendererBackend,
+      pixelWidth: rendererResult.pixelWidth,
+      pixelHeight: rendererResult.pixelHeight,
+      sha256,
+      renderProfileHash: rendererResult.renderProfileHash,
+    };
+    const parsedResult = parseScreenshotResult(
+      publicResultCandidate,
+      'Screenshot result validation failed.',
+    );
+    // Re-narrow `sha256` after the parse instead of asserting through a
+    // type cast. If `ScreenshotResultSchema` is ever changed to strip or
+    // transform `sha256`, this invariant catches it instead of silently
+    // hiding the regression.
+    invariant(
+      parsedResult.sha256 !== undefined,
+      'parsed screenshot result must preserve sha256',
+    );
+    const publicResult: CapturedScreenshotResult = {
+      ...parsedResult,
+      sha256: parsedResult.sha256,
+    };
+
+    await rename(temporaryOutputPath, finalArtifactPath);
+    await appendArtifact(
+      options.sessionDir,
+      createArtifactEntry({
+        kind: 'screenshot',
+        filename,
+        sessionId: publicResult.sessionId,
+        capturedAtSeq: publicResult.capturedAtSeq,
+        sha256,
+        metadata: {
+          profileName: publicResult.profileName,
+          cols: publicResult.cols,
+          rows: publicResult.rows,
+          pngSizeBytes: publicResult.pngSizeBytes,
+          cursorVisible: publicResult.cursorVisible,
+          rendererBackend: publicResult.rendererBackend,
+          pixelWidth: publicResult.pixelWidth,
+          pixelHeight: publicResult.pixelHeight,
+          renderProfileHash: publicResult.renderProfileHash,
+        },
+      }),
+    );
+
+    return publicResult;
+  } catch (error) {
+    await rm(temporaryOutputPath, { force: true }).catch(() => undefined);
+    throw error;
+  }
+}
diff --git a/test/unit/commands/screenshot.test.ts b/test/unit/commands/screenshot.test.ts
index c28abc9..0844f5f 100644
--- a/test/unit/commands/screenshot.test.ts
+++ b/test/unit/commands/screenshot.test.ts
@@ -363,38 +363,9 @@ describe('screenshot command', () => {
       },
       expect.any(Function),
     );
-    expect(mocks.rename).toHaveBeenCalledWith(
-      expect.stringMatching(/^\/artifacts\/\.tmp-screenshot-.*\.png$/),
-      '/artifacts/screenshot-5-reference-dark.png',
-    );
-    expect(mocks.createArtifactEntry).toHaveBeenCalledWith({
-      kind: 'screenshot',
-      filename: 'screenshot-5-reference-dark.png',
-      sessionId: 'session-01',
-      capturedAtSeq: 5,
-      sha256: TEST_SCREENSHOT_SHA256,
-      metadata: {
-        profileName: 'reference-dark',
-        cols: 80,
-        rows: 24,
-        pngSizeBytes: 2048,
-        cursorVisible: false,
-        rendererBackend: 'ghostty-web',
-        pixelWidth: 800,
-        pixelHeight: 600,
-        renderProfileHash: TEST_RENDER_PROFILE_HASH,
-      },
-    });
-    expect(mocks.appendArtifact).toHaveBeenCalledWith(
-      '/tmp/agent-tty/sessions/session-01',
-      expect.objectContaining({
-        kind: 'screenshot',
-        filename: 'screenshot-5-reference-dark.png',
-        sessionId: 'session-01',
-        capturedAtSeq: 5,
-        sha256: TEST_SCREENSHOT_SHA256,
-      }),
-    );
+    // Rename, manifest-entry construction, and manifest append are exercised
+    // by `test/unit/screenshot/capture.test.ts`. Here we only check the
+    // routing-level surface of the offline path.
     expect(mocks.emitSuccess).toHaveBeenCalledWith({
       command: 'screenshot',
       json: false,
@@ -462,14 +433,9 @@ describe('screenshot command', () => {
       expect.stringMatching(/^\/artifacts\/\.tmp-screenshot-.*\.png$/),
       { showCursor: true },
     );
-    expect(mocks.createArtifactEntry).toHaveBeenCalled();
-    const artifactEntryArg = mocks.createArtifactEntry.mock.calls.at(
-      -1,
-    )?.[0] as {
-      metadata?: { cursorVisible?: boolean };
-    };
-    expect(artifactEntryArg.metadata?.cursorVisible).toBe(true);
-
+    // Manifest-entry metadata for `cursorVisible` is exercised by
+    // `test/unit/screenshot/capture.test.ts`; here we only check that the
+    // command-level result reflects the requested `showCursor` value.
     expect(mocks.emitSuccess).toHaveBeenCalled();
     const emitSuccessArg = mocks.emitSuccess.mock.calls.at(-1)?.[0] as {
       result?: { cursorVisible?: boolean };
diff --git a/test/unit/screenshot/capture.test.ts b/test/unit/screenshot/capture.test.ts
new file mode 100644
index 0000000..b52ae8e
--- /dev/null
+++ b/test/unit/screenshot/capture.test.ts
@@ -0,0 +1,543 @@
+import { access, mkdir, readFile, writeFile } from 'node:fs/promises';
+import { dirname } from 'node:path';
+
+import { describe, expect, it, vi } from 'vitest';
+
+import { createTemporarySessionDir } from '../../helpers.js';
+
+import type { RendererBackend } from '../../../src/renderer/backend.js';
+import type { ScreenshotResult } from '../../../src/protocol/messages.js';
+import type {
+  ReplayInput,
+  ReplayState,
+  SemanticSnapshot,
+} from '../../../src/renderer/types.js';
+
+import {
+  captureScreenshotResult,
+  parseScreenshotResult,
+} from '../../../src/screenshot/capture.js';
+import { readArtifactManifest } from '../../../src/storage/artifactManifest.js';
+import {
+  artifactPath,
+  screenshotFilename,
+} from '../../../src/storage/artifactPaths.js';
+
+const TEST_SHA256 = 'a'.repeat(64);
+const TEST_RENDER_PROFILE_HASH = 'b'.repeat(64);
+// First four bytes of the PNG magic signature (0x89 'P' 'N' 'G'). Enough to
+// satisfy the test that we wrote/read the same buffer; the renderer
+// produces a real PNG, but these unit tests do not validate the format.
+const PNG_HEADER = Buffer.from([0x89, 0x50, 0x4e, 0x47]);
+
+interface FakeBackendOptions {
+  resultOverrides?: Partial<ScreenshotResult>;
+  writePng?: boolean;
+  fail?: Error;
+  onScreenshot?: (
+    outputPath: string,
+    options?: { showCursor?: boolean },
+  ) => void;
+}
+
+function createFakeBackend(options: FakeBackendOptions = {}): RendererBackend {
+  const writePng = options.writePng ?? true;
+
+  return {
+    rendererBackend: 'fake-renderer',
+    isBooted: false,
+    boot: vi.fn().mockResolvedValue(undefined),
+    replayTo: vi.fn(
+      (input: ReplayInput): Promise<ReplayState> =>
+        Promise.resolve({
+          lastSeq: input.targetSeq,
+          cols: input.initialCols,
+          rows: input.initialRows,
+          cursorRow: 0,
+          cursorCol: 0,
+        }),
+    ),
+    snapshot: vi.fn(
+      (): Promise<SemanticSnapshot> =>
+        Promise.resolve({
+          sessionId: 'session-01',
+          capturedAtSeq: 0,
+          cols: 80,
+          rows: 24,
+          cursorRow: 0,
+          cursorCol: 0,
+          isAltScreen: false,
+          visibleLines: [],
+        }),
+    ),
+    screenshot: vi.fn(
+      async (
+        outputPath: string,
+        screenshotOptions?: { showCursor?: boolean },
+      ): Promise<ScreenshotResult> => {
+        options.onScreenshot?.(outputPath, screenshotOptions);
+        if (options.fail !== undefined) {
+          throw options.fail;
+        }
+        if (writePng) {
+          await writeFile(outputPath, PNG_HEADER);
+        }
+        return {
+          sessionId: 'session-01',
+          capturedAtSeq: 5,
+          profileName: 'reference-dark',
+          cols: 80,
+          rows: 24,
+          artifactPath: outputPath,
+          pngSizeBytes: 4,
+          cursorVisible: screenshotOptions?.showCursor === true,
+          rendererBackend: 'fake-renderer',
+          pixelWidth: 800,
+          pixelHeight: 600,
+          sha256: TEST_SHA256,
+          renderProfileHash: TEST_RENDER_PROFILE_HASH,
+          ...options.resultOverrides,
+        };
+      },
+    ),
+    getVisibleText: vi.fn().mockResolvedValue(''),
+    dispose: vi.fn().mockResolvedValue(undefined),
+  };
+}
+
+async function createSessionDir(sessionId = 'session-01'): Promise<string> {
+  return await createTemporarySessionDir(
+    'agent-tty-screenshot-capture-',
+    sessionId,
+  );
+}
+
+describe('parseScreenshotResult', () => {
+  it('returns the validated screenshot result on success', () => {
+    const result = parseScreenshotResult({
+      sessionId: 'session-01',
+      capturedAtSeq: 5,
+      profileName: 'reference-dark',
+      cols: 80,
+      rows: 24,
+      artifactPath: '/tmp/screenshot.png',
+      pngSizeBytes: 4,
+      sha256: TEST_SHA256,
+    });
+
+    expect(result.sessionId).toBe('session-01');
+    expect(result.sha256).toBe(TEST_SHA256);
+  });
+
+  it('throws PROTOCOL_ERROR with the supplied message on schema failure', () => {
+    expect(() =>
+      parseScreenshotResult(
+        {
+          sessionId: 'session-01',
+          capturedAtSeq: 5,
+          // missing profileName, cols, rows, artifactPath, pngSizeBytes
+        },
+        'custom error message',
+      ),
+    ).toThrow(
+      expect.objectContaining({
+        code: 'PROTOCOL_ERROR',
+        message: 'custom error message',
+      }) as object,
+    );
+  });
+
+  it('uses a default message when none is supplied', () => {
+    expect(() => parseScreenshotResult({})).toThrow(
+      expect.objectContaining({
+        code: 'PROTOCOL_ERROR',
+        message: 'Unexpected response from host',
+      }) as object,
+    );
+  });
+});
+
+describe('screenshot capture', () => {
+  it('writes the PNG to the final artifact path and returns a typed result', async () => {
+    const sessionDirectory = await createSessionDir();
+    const backend = createFakeBackend();
+
+    const result = await captureScreenshotResult({
+      backend,
+      sessionDir: sessionDirectory,
+      profileName: 'reference-dark',
+      expectedSessionId: 'session-01',
+    });
+
+    const expectedFilename = screenshotFilename(5, 'reference-dark');
+    const expectedPath = artifactPath(sessionDirectory, expectedFilename);
+
+    expect(result).toEqual({
+      sessionId: 'session-01',
+      capturedAtSeq: 5,
+      profileName: 'reference-dark',
+      cols: 80,
+      rows: 24,
+      artifactPath: expectedPath,
+      pngSizeBytes: 4,
+      cursorVisible: false,
+      rendererBackend: 'fake-renderer',
+      pixelWidth: 800,
+      pixelHeight: 600,
+      sha256: TEST_SHA256,
+      renderProfileHash: TEST_RENDER_PROFILE_HASH,
+    });
+
+    await expect(access(expectedPath)).resolves.toBeUndefined();
+    await expect(readFile(expectedPath)).resolves.toEqual(PNG_HEADER);
+
+    const manifest = await readArtifactManifest(sessionDirectory);
+    expect(manifest.artifacts).toHaveLength(1);
+    expect(manifest.artifacts[0]).toMatchObject({
+      kind: 'screenshot',
+      filename: expectedFilename,
+      sessionId: 'session-01',
+      capturedAtSeq: 5,
+      sha256: TEST_SHA256,
+      metadata: {
+        profileName: 'reference-dark',
+        cols: 80,
+        rows: 24,
+        pngSizeBytes: 4,
+        cursorVisible: false,
+        rendererBackend: 'fake-renderer',
+        pixelWidth: 800,
+        pixelHeight: 600,
+        renderProfileHash: TEST_RENDER_PROFILE_HASH,
+      },
+    });
+  });
+
+  it('omits screenshot options when showCursor is undefined and threads it when set', async () => {
+    const sessionDirectory = await createSessionDir();
+    const observed: Array<{
+      outputPath: string;
+      options: { showCursor?: boolean } | undefined;
+    }> = [];
+    const backend = createFakeBackend({
+      onScreenshot: (outputPath, screenshotOptions) => {
+        observed.push({ outputPath, options: screenshotOptions });
+      },
+    });
+
+    await captureScreenshotResult({
+      backend,
+      sessionDir: sessionDirectory,
+      profileName: 'reference-dark',
+      expectedSessionId: 'session-01',
+    });
+
+    expect(observed.at(-1)?.options).toBeUndefined();
+
+    const sessionDirectory2 = await createSessionDir('session-02');
+    const backendWithCursor = createFakeBackend({
+      onScreenshot: (outputPath, screenshotOptions) => {
+        observed.push({ outputPath, options: screenshotOptions });
+      },
+      resultOverrides: { sessionId: 'session-02' },
+    });
+
+    const cursorResult = await captureScreenshotResult({
+      backend: backendWithCursor,
+      sessionDir: sessionDirectory2,
+      profileName: 'reference-dark',
+      expectedSessionId: 'session-02',
+      showCursor: true,
+    });
+
+    expect(observed.at(-1)?.options).toEqual({ showCursor: true });
+    expect(cursorResult.cursorVisible).toBe(true);
+
+    // showCursor: false must be threaded through as a distinct value (not
+    // collapsed to undefined). Guards against the ternary regressing to a
+    // truthy-only check.
+    const sessionDirectoryFalse = await createSessionDir('session-03');
+    const backendShowFalse = createFakeBackend({
+      onScreenshot: (outputPath, screenshotOptions) => {
+        observed.push({ outputPath, options: screenshotOptions });
+      },
+      resultOverrides: { sessionId: 'session-03' },
+    });
+
+    const falseResult = await captureScreenshotResult({
+      backend: backendShowFalse,
+      sessionDir: sessionDirectoryFalse,
+      profileName: 'reference-dark',
+      expectedSessionId: 'session-03',
+      showCursor: false,
+    });
+
+    expect(observed.at(-1)?.options).toEqual({ showCursor: false });
+    expect(falseResult.cursorVisible).toBe(false);
+  });
+
+  it('rejects empty sessionDir, profileName, or expectedSessionId before invoking the backend', async () => {
+    const sessionDirectory = await createSessionDir();
+    const observed: Array<string> = [];
+    const backend = createFakeBackend({
+      onScreenshot: (outputPath) => {
+        observed.push(outputPath);
+      },
+    });
+
+    await expect(
+      captureScreenshotResult({
+        backend,
+        sessionDir: '',
+        profileName: 'reference-dark',
+        expectedSessionId: 'session-01',
+      }),
+    ).rejects.toThrow(/sessionDir must be non-empty/u);
+
+    await expect(
+      captureScreenshotResult({
+        backend,
+        sessionDir: sessionDirectory,
+        profileName: '',
+        expectedSessionId: 'session-01',
+      }),
+    ).rejects.toThrow(/profileName must be non-empty/u);
+
+    await expect(
+      captureScreenshotResult({
+        backend,
+        sessionDir: sessionDirectory,
+        profileName: 'reference-dark',
+        expectedSessionId: '',
+      }),
+    ).rejects.toThrow(/expectedSessionId must be non-empty/u);
+
+    expect(observed).toEqual([]);
+  });
+
+  // Each invariant gets its own test so that a single failure does not
+  // mask the others. Using `it.each` keeps the table-driven readability
+  // while reporting one independent test per row.
+  it.each([
+    {
+      name: 'sessionId mismatch',
+      overrides: { sessionId: 'other-session' } as Partial<ScreenshotResult>,
+      pattern: /sessionId must match expected sessionId/u,
+    },
+    {
+      name: 'profileName mismatch',
+      overrides: {
+        profileName: 'reference-light',
+      } as Partial<ScreenshotResult>,
+      pattern: /profileName must match the requested profile/u,
+    },
+    {
+      // pngSizeBytes is asserted before the schema runs, so passing 0
+      // exercises the runtime invariant the same way a buggy backend would.
+      name: 'non-positive pngSizeBytes',
+      overrides: { pngSizeBytes: 0 } as Partial<ScreenshotResult>,
+      pattern: /pngSizeBytes must be positive/u,
+    },
+    {
+      name: 'mismatched artifactPath',
+      overrides: {
+        artifactPath: '/wrong/path.png',
+      } as Partial<ScreenshotResult>,
+      pattern: /path must match the requested output path/u,
+    },
+    {
+      name: 'missing sha256',
+      overrides: { sha256: undefined } as Partial<ScreenshotResult>,
+      pattern: /must produce sha256/u,
+    },
+  ])(
+    'rejects $name and removes the temp file before any persistence',
+    async ({ name, overrides, pattern }) => {
+      const sessionId = `session-inv-${name.replace(/\W+/gu, '-')}`;
+      const sessionDirectory = await createSessionDir(sessionId);
+      let observedTempPath: string | undefined;
+      const backend = createFakeBackend({
+        resultOverrides: {
+          ...overrides,
+          sessionId: overrides.sessionId ?? sessionId,
+        },
+        onScreenshot: (outputPath) => {
+          observedTempPath = outputPath;
+        },
+      });
+
+      await expect(
+        captureScreenshotResult({
+          backend,
+          sessionDir: sessionDirectory,
+          profileName: 'reference-dark',
+          expectedSessionId: sessionId,
+        }),
+      ).rejects.toThrow(pattern);
+
+      const manifest = await readArtifactManifest(sessionDirectory);
+      expect(manifest.artifacts).toEqual([]);
+      // The temp file written by the fake backend should have been removed.
+      expect(observedTempPath).toMatch(
+        /\/artifacts\/\.tmp-screenshot-.*\.png$/u,
+      );
+      if (observedTempPath !== undefined) {
+        await expect(access(observedTempPath)).rejects.toMatchObject({
+          code: 'ENOENT',
+        });
+      }
+      // The final filename should not exist either since rename never ran.
+      await expect(
+        access(
+          artifactPath(
+            sessionDirectory,
+            screenshotFilename(5, 'reference-dark'),
+          ),
+        ),
+      ).rejects.toMatchObject({ code: 'ENOENT' });
+    },
+  );
+
+  it('rejects malformed public results before rename or manifest append', async () => {
+    const sessionDirectory = await createSessionDir();
+    const backend = createFakeBackend({
+      // cols=0 passes the runtime invariants but trips the strict
+      // ScreenshotResultSchema PositiveIntSchema validation.
+      resultOverrides: { cols: 0 },
+    });
+
+    await expect(
+      captureScreenshotResult({
+        backend,
+        sessionDir: sessionDirectory,
+        profileName: 'reference-dark',
+        expectedSessionId: 'session-01',
+      }),
+    ).rejects.toMatchObject({
+      code: 'PROTOCOL_ERROR',
+      message: 'Screenshot result validation failed.',
+      details: { issues: expect.any(Array) as unknown },
+    });
+
+    const manifest = await readArtifactManifest(sessionDirectory);
+    expect(manifest.artifacts).toEqual([]);
+    await expect(
+      access(
+        artifactPath(sessionDirectory, screenshotFilename(5, 'reference-dark')),
+      ),
+    ).rejects.toMatchObject({ code: 'ENOENT' });
+  });
+
+  it('removes the temp file when rename fails after a successful render', async () => {
+    const sessionDirectory = await createSessionDir();
+    const finalFilename = screenshotFilename(5, 'reference-dark');
+    const finalPath = artifactPath(sessionDirectory, finalFilename);
+    // Pre-create a non-empty directory at the final destination so rename
+    // cannot replace it with the temp file (ENOTEMPTY/EISDIR on POSIX).
+    await mkdir(finalPath, { recursive: true });
+    await writeFile(`${finalPath}/blocker`, 'present');
+
+    let observedTempPath: string | undefined;
+    const backend = createFakeBackend({
+      onScreenshot: (outputPath) => {
+        observedTempPath = outputPath;
+      },
+    });
+
+    await expect(
+      captureScreenshotResult({
+        backend,
+        sessionDir: sessionDirectory,
+        profileName: 'reference-dark',
+        expectedSessionId: 'session-01',
+      }),
+    ).rejects.toThrow();
+
+    expect(observedTempPath).toMatch(/\/artifacts\/\.tmp-screenshot-.*\.png$/u);
+    if (observedTempPath !== undefined) {
+      await expect(access(observedTempPath)).rejects.toMatchObject({
+        code: 'ENOENT',
+      });
+    }
+    const manifest = await readArtifactManifest(sessionDirectory);
+    expect(manifest.artifacts).toEqual([]);
+  });
+
+  it('preserves the renamed final PNG when manifest append fails after rename', async () => {
+    const sessionDirectory = await createSessionDir();
+    const finalFilename = screenshotFilename(5, 'reference-dark');
+    const finalPath = artifactPath(sessionDirectory, finalFilename);
+    // Pre-write a manifest whose sessionId does not match the directory so
+    // `appendArtifact` raises a MANIFEST_VALIDATION_ERROR after the temp file
+    // has already been renamed into place.
+    const manifestFilePath = artifactPath(sessionDirectory, 'manifest.json');
+    await mkdir(dirname(manifestFilePath), { recursive: true });
+    await writeFile(
+      manifestFilePath,
+      `${JSON.stringify({
+        version: 1,
+        sessionId: 'unrelated-session',
+        artifacts: [],
+      })}\n`,
+    );
+
+    let observedTempPath: string | undefined;
+    const backend = createFakeBackend({
+      onScreenshot: (outputPath) => {
+        observedTempPath = outputPath;
+      },
+    });
+
+    await expect(
+      captureScreenshotResult({
+        backend,
+        sessionDir: sessionDirectory,
+        profileName: 'reference-dark',
+        expectedSessionId: 'session-01',
+      }),
+    ).rejects.toMatchObject({ code: 'MANIFEST_VALIDATION_ERROR' });
+
+    // The final PNG survives because cleanup only removes the temp file,
+    // not the already-renamed artifact. This is intentional: the rename
+    // succeeded, so the PNG is valid; only the manifest entry is missing.
+    // Adding rename rollback is not addressed in this refactor; the
+    // follow-up is tracked in #79.
+    await expect(access(finalPath)).resolves.toBeUndefined();
+    if (observedTempPath !== undefined) {
+      await expect(access(observedTempPath)).rejects.toMatchObject({
+        code: 'ENOENT',
+      });
+    }
+  });
+
+  it('removes the temp file and rethrows when the renderer screenshot rejects', async () => {
+    const sessionDirectory = await createSessionDir();
+    const captureError = new Error('renderer crashed');
+    let observedTempPath: string | undefined;
+    const backend = createFakeBackend({
+      writePng: false,
+      onScreenshot: (outputPath) => {
+        observedTempPath = outputPath;
+      },
+      fail: captureError,
+    });
+
+    await expect(
+      captureScreenshotResult({
+        backend,
+        sessionDir: sessionDirectory,
+        profileName: 'reference-dark',
+        expectedSessionId: 'session-01',
+      }),
+    ).rejects.toBe(captureError);
+
+    expect(observedTempPath).toMatch(/\/artifacts\/\.tmp-screenshot-.*\.png$/u);
+    if (observedTempPath !== undefined) {
+      await expect(access(observedTempPath)).rejects.toMatchObject({
+        code: 'ENOENT',
+      });
+    }
+    const manifest = await readArtifactManifest(sessionDirectory);
+    expect(manifest.artifacts).toEqual([]);
+  });
+});