chore: package send sandbox evidence gate

docs/source-discovery/2026-07-10-send-sandbox-gate.md

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+# Send Sandbox Gate
+
+Date: 2026-07-10
+Node: R6c online sandbox-send evidence gate
+
+## Local constraint
+
+The local development environment cannot log in to iSphere / IMPlatformClient because it has no reachable service endpoint. Therefore R6c cannot be completed by a local live send.
+
+Decision for this loop: prepare a returnable online sandbox evidence package instead of attempting any local send.
+
+## Package produced
+
+Script:
+
+```powershell
+powershell -NoProfile -ExecutionPolicy Bypass -File scripts\package-send-sandbox-gate.ps1
+```
+
+Verification:
+
+```powershell
+powershell -NoProfile -ExecutionPolicy Bypass -File scripts\verify-send-sandbox-gate-package.ps1
+```
+
+Generated package:
+
+```text
+runs/send-sandbox-gate-package/
+runs/send-sandbox-gate-package.zip
+```
+
+The package embeds the existing read-only live probe recorder under:
+
+```text
+recorder/ISphereLiveProbeRecorder.exe
+recorder/variants/ISphereLiveProbeRecorder-x86.exe
+```
+
+## Package files
+
+| File | Purpose |
+| --- | --- |
+| `README.txt` | Explains local login limitation, online sandbox requirement, and one-send rule. |
+| `OPERATOR-STEPS.md` | Step-by-step operator procedure. |
+| `SANDBOX-SEND-INPUTS.template.json` | Template for sandbox target, content hash, idempotency key, and observed result. |
+| `EXPECTED-RETURN-FILES.txt` | Return package acceptance checklist. |
+| `run-before-recorder.bat` | Runs read-only recorder before the manual sandbox send. |
+| `run-after-recorder.bat` | Runs read-only recorder after the manual sandbox send. |
+| `compute-content-hash.ps1` | Computes SHA256 for the exact test message body. |
+| `make-return-zip.ps1` | Creates the return zip after before/after recordings and input JSON are present. |
+
+## Operator rules
+
+The package encodes these explicit markers:
+
+```text
+LOCAL_LOGIN_UNAVAILABLE
+ONLINE_SANDBOX_REQUIRED
+MANUAL_ONE_SEND_ONLY
+DO_NOT_SEND_SECOND_TIME
+content_sha256
+idempotency_key
+success_ack_or_sent_record
+```
+
+Required online procedure:
+
+1. Log in normally on an online/internal sandbox machine.
+2. Fill `SANDBOX-SEND-INPUTS.json` from the template.
+3. Run `run-before-recorder.bat`.
+4. Manually send exactly one message to the declared sandbox target.
+5. Record `success_ack_or_sent_record`.
+6. Do not send a second copy.
+7. Run `run-after-recorder.bat`.
+8. Run `make-return-zip.ps1`.
+9. Return the generated zip.
+
+## Safety boundary
+
+The package does not:
+
+- send messages automatically;
+- upload files;
+- click or type;
+- inject or hook;
+- capture network traffic;
+- enable production send.
+
+The only send action is the operator's one manual sandbox send inside the official client.
+
+## Acceptance gate
+
+R6c can pass only after a returned package proves all of the following:
+
+- explicit sandbox target;
+- exactly one content hash;
+- exactly one idempotency key;
+- observed success/ack or local sent-record evidence;
+- confirmation that no second send was made;
+- before/after read-only recorder outputs are present.
+
+## Current decision
+
+R6c local-preparation slice is complete, but the full online evidence gate is not passed yet.
+
+Production `isphere_send_message` remains blocked.
+
+Next node: **R6d returned sandbox evidence intake** after the user returns the generated package.