feat(web): name context sources and mark steering in the transcript

Every logged non-user user/message collapsed into one identical
「上下文注入」 row, and mid-turn steering rendered in exactly the bubble a
turn-opening prompt uses, so the transcript could not say what had been
added or which message interrupted a running turn.

TranscriptAdapter and the history fold now attach a provenance view to
each context node, computed by contextProvenance() from the durable
source alone: a role (inject, or recall for a cross-session snapshot)
and a producer name read out of the log — instruction paths for
workspace-instructions, session titles for session-reference, the plugin
id for a plugin source, and the bare kind for any other. No client-side
table of producer names, so a renamed or newly mounted producer stays
identifiable without a client release and a foreign log projects like a
live one. ContextInjectionRow titles itself from the role and shows the
name beside it; MessageItem captions durable and pending steering
bubbles.

The caption reverses one clause of the no-interjection-chrome decision,
which removed it because the composer could not steer; composer steering
shipped afterwards without amending that note, so this change supplies
the product decision its reintroduction clause required and corrects the
stale facts left in it.

Fixes #1291

apps/web/tests/seeded-history.e2e.ts

@@ -236,7 +236,10 @@ describe('web e2e: seeded history renders through cold resume', () => {
         }],
       },
     }))
-    await page.getByRole('button', { name: 'Context injection' }).waitFor({ timeout: 10_000 })
+    // The header names the producer the durable source records, so the
+    // reconciled instruction file is readable without expanding the row.
+    await page.getByRole('button', { name: 'Context injection · AGENTS.md', exact: true })
+      .waitFor({ timeout: 10_000 })
   }, 60_000)
 
   it.skipIf(MODE === 'record')('matches the historical conversation aria golden', async () => {
@@ -254,7 +257,7 @@ describe('web e2e: seeded history renders through cold resume', () => {
 
   it.skipIf(MODE === 'record')('matches the Figma context disclosure geometry', async () => {
     onTestFailed(() => saveFailureShot(page, 'web-e2e-context-injection'))
-    const disclosure = page.getByRole('button', { name: 'Context injection' })
+    const disclosure = page.getByRole('button', { name: 'Context injection · AGENTS.md', exact: true })
     expect(await disclosure.getAttribute('aria-expanded')).toBe('false')
     const collapsedIcon = disclosure.locator('svg').first()
     const collapsedIconBox = await collapsedIcon.boundingBox()
@@ -365,9 +368,8 @@ describe('web e2e: seeded history renders through cold resume', () => {
       source: { kind: 'plugin', plugin: 'fixture' },
     }))
 
-    const disclosures = page.getByRole('button', { name: 'Context injection' })
-    await expect.poll(() => disclosures.count(), { timeout: 10_000 }).toBe(2)
-    const disclosure = disclosures.nth(1)
+    const disclosure = page.getByRole('button', { name: 'Context injection · fixture', exact: true })
+    await disclosure.waitFor({ timeout: 10_000 })
     await disclosure.click()
     await expect.poll(() => disclosure.getAttribute('aria-expanded')).toBe('true')
 

apps/web/tests/snapshots/bash-abort-row/ui.expected.md

@@ -10,10 +10,10 @@
 - button "Branch into a new conversation" [disabled]:
   - img
 - text: Available only on the last message of a completed turn
-- button "Context injection":
+- button "Context injection · @deepseek-ai/dsh-system-prompt":
   - img
   - img
-  - text: Context injection
+  - text: Context injection · @deepseek-ai/dsh-system-prompt
 - 'button "Failed Bash Error: command aborted" [expanded]':
   - img
   - text: "Failed Bash Error: command aborted"

apps/web/tests/snapshots/code-mode-round/ui.expected.md

@@ -10,10 +10,10 @@
 - button "Branch into a new conversation" [disabled]:
   - img
 - text: Available only on the last message of a completed turn
-- button "Context injection":
+- button "Context injection · @deepseek-ai/dsh-system-prompt":
   - img
   - img
-  - text: Context injection
+  - text: Context injection · @deepseek-ai/dsh-system-prompt
 - 'button "Think The user wants me to write a single `run_code` program that:"':
   - img
   - img

apps/web/tests/snapshots/cordis-tool-round/ui.expected.md

@@ -10,10 +10,10 @@
 - button "Branch into a new conversation" [disabled]:
   - img
 - text: Available only on the last message of a completed turn
-- button "Context injection":
+- button "Context injection · @deepseek-ai/dsh-system-prompt":
   - img
   - img
-  - text: Context injection
+  - text: Context injection · @deepseek-ai/dsh-system-prompt
 - button "Think The user wants me to:":
   - img
   - img

apps/web/tests/snapshots/fresh-round-trip/ui.expected.md

@@ -10,10 +10,10 @@
 - button "Branch into a new conversation" [disabled]:
   - img
 - text: Available only on the last message of a completed turn
-- button "Context injection":
+- button "Context injection · @deepseek-ai/dsh-system-prompt":
   - img
   - img
-  - text: Context injection
+  - text: Context injection · @deepseek-ai/dsh-system-prompt
 - button "Think The user wants me to run a simple bash command and reply with \"DONE\".":
   - img
   - img

apps/web/tests/snapshots/lifecycle-chrome/reloaded.expected.md

@@ -10,10 +10,10 @@
 - button "Branch into a new conversation" [disabled]:
   - img
 - text: Available only on the last message of a completed turn
-- button "Context injection":
+- button "Context injection · @deepseek-ai/dsh-system-prompt":
   - img
   - img
-  - text: Context injection
+  - text: Context injection · @deepseek-ai/dsh-system-prompt
 - button "Think The user wants me to reply with a single word. Let me comply.":
   - img
   - img

apps/web/tests/snapshots/live-interactions/cancel.expected.md

@@ -10,10 +10,10 @@
 - button "Branch into a new conversation" [disabled]:
   - img
 - text: Available only on the last message of a completed turn
-- button "Context injection":
+- button "Context injection · @deepseek-ai/dsh-system-prompt":
   - img
   - img
-  - text: Context injection
+  - text: Context injection · @deepseek-ai/dsh-system-prompt
 - paragraph: partial
 - text: Stopped
 - button "Copy":

apps/web/tests/snapshots/live-interactions/error-auth.expected.md

@@ -10,10 +10,10 @@
 - button "Branch into a new conversation" [disabled]:
   - img
 - text: Available only on the last message of a completed turn
-- button "Context injection":
+- button "Context injection · @deepseek-ai/dsh-system-prompt":
   - img
   - img
-  - text: Context injection
+  - text: Context injection · @deepseek-ai/dsh-system-prompt
 - status:
   - text: This turn failedAPI key is invalid
   - code: AUTH

apps/web/tests/snapshots/live-interactions/loading.expected.md

@@ -10,10 +10,10 @@
 - button "Branch into a new conversation" [disabled]:
   - img
 - text: Available only on the last message of a completed turn
-- button "Context injection":
+- button "Context injection · @deepseek-ai/dsh-system-prompt":
   - img
   - img
-  - text: Context injection
+  - text: Context injection · @deepseek-ai/dsh-system-prompt
 - paragraph: partial
 - status: Deep diving...
 - textbox "Message the agent"

apps/web/tests/snapshots/live-interactions/retry.expected.md

@@ -10,10 +10,10 @@
 - button "Branch into a new conversation" [disabled]:
   - img
 - text: Available only on the last message of a completed turn
-- button "Context injection":
+- button "Context injection · @deepseek-ai/dsh-system-prompt":
   - img
   - img
-  - text: Context injection
+  - text: Context injection · @deepseek-ai/dsh-system-prompt
 - group:
   - status: Retried model request (1/2) · {{duration}}
 - button "Think The user is asking for a one-sentence description of event sourcing. This is a straightforward knowledge question that doesn't require any skill loading or tool calls.":

apps/web/tests/snapshots/plan-review/approved.expected.md

@@ -11,10 +11,10 @@
 - button "Branch into a new conversation" [disabled]:
   - img
 - text: Available only on the last message of a completed turn
-- button "Context injection":
+- button "Context injection · @deepseek-ai/dsh-system-prompt":
   - img
   - img
-  - text: Context injection
+  - text: Context injection · @deepseek-ai/dsh-system-prompt
 - 'button "Think The user wants me to plan a small change to add a `--greeting` flag to a CLI. They explicitly told me not to read or write any files, and to call exit_plan_mode with a short plan. Let me do that directly."':
   - img
   - img

apps/web/tests/snapshots/question-composer/answered.expected.md

@@ -10,10 +10,10 @@
 - button "Branch into a new conversation" [disabled]:
   - img
 - text: Available only on the last message of a completed turn
-- button "Context injection":
+- button "Context injection · @deepseek-ai/dsh-system-prompt":
   - img
   - img
-  - text: Context injection
+  - text: Context injection · @deepseek-ai/dsh-system-prompt
 - button "Think The user wants me to use the ask_user_question tool with specific parameters. Let me do exactly that.":
   - img
   - img

apps/web/tests/snapshots/queue-actions/collapsed.expected.md

@@ -10,10 +10,10 @@
 - button "Branch into a new conversation" [disabled]:
   - img
 - text: Available only on the last message of a completed turn
-- button "Context injection":
+- button "Context injection · @deepseek-ai/dsh-system-prompt":
   - img
   - img
-  - text: Context injection
+  - text: Context injection · @deepseek-ai/dsh-system-prompt
 - paragraph: partial
 - status: Deep diving...
 - button "2 queued messages"

apps/web/tests/snapshots/queue-actions/editing.expected.md

@@ -10,10 +10,10 @@
 - button "Branch into a new conversation" [disabled]:
   - img
 - text: Available only on the last message of a completed turn
-- button "Context injection":
+- button "Context injection · @deepseek-ai/dsh-system-prompt":
   - img
   - img
-  - text: Context injection
+  - text: Context injection · @deepseek-ai/dsh-system-prompt
 - paragraph: partial
 - status: Deep diving...
 - button "2 queued messages" [disabled] [expanded]

apps/web/tests/snapshots/queue-actions/layout.expected.md

@@ -8,18 +8,18 @@
   - img
   - img
   - text: "goal Goal created Status: active Objective: Keep the composer context panels aligned Rounds: 0/256 Activation: armed Commands: /goal edit <objective>, /goal pause, /goal clear"
-- button "Context injection":
+- button "Context injection · goal":
   - img
   - img
-  - text: Context injection
-- button "Context injection":
+  - text: Context injection · goal
+- button "Context injection · goal":
   - img
   - img
-  - text: Context injection
-- button "Context injection":
+  - text: Context injection · goal
+- button "Context injection · @deepseek-ai/dsh-system-prompt":
   - img
   - img
-  - text: Context injection
+  - text: Context injection · @deepseek-ai/dsh-system-prompt
 - paragraph: partial
 - status: Deep diving...
 - region "To-dos":

apps/web/tests/snapshots/queue-actions/preserved.expected.md

@@ -10,10 +10,10 @@
 - button "Branch into a new conversation" [disabled]:
   - img
 - text: Available only on the last message of a completed turn
-- button "Context injection":
+- button "Context injection · @deepseek-ai/dsh-system-prompt":
   - img
   - img
-  - text: Context injection
+  - text: Context injection · @deepseek-ai/dsh-system-prompt
 - paragraph: partial
 - text: Stopped
 - button "Copy":

apps/web/tests/snapshots/queue-actions/ui.expected.md

@@ -10,10 +10,10 @@
 - button "Branch into a new conversation" [disabled]:
   - img
 - text: Available only on the last message of a completed turn
-- button "Context injection":
+- button "Context injection · @deepseek-ai/dsh-system-prompt":
   - img
   - img
-  - text: Context injection
+  - text: Context injection · @deepseek-ai/dsh-system-prompt
 - paragraph: partial
 - status: Deep diving...
 - list:

apps/web/tests/snapshots/seeded-history/command-row.expected.md

@@ -37,10 +37,10 @@
 - button "Context compacted View compaction summary":
   - img
   - text: Context compacted View compaction summary
-- button "Context injection":
+- button "Context injection · AGENTS.md":
   - img
   - img
-  - text: Context injection
+  - text: Context injection · AGENTS.md
 - img
 - text: permission preset read-only
 - textbox "Message the agent"

apps/web/tests/snapshots/seeded-history/ui.expected.md

@@ -37,10 +37,10 @@
 - button "Context compacted View compaction summary":
   - img
   - text: Context compacted View compaction summary
-- button "Context injection":
+- button "Context injection · AGENTS.md":
   - img
   - img
-  - text: Context injection
+  - text: Context injection · AGENTS.md
 - textbox "Message the agent"
 - button "Commands":
   - img

apps/web/tests/snapshots/steering/mid-steer.expected.md

@@ -10,10 +10,10 @@
 - button "Branch into a new conversation" [disabled]:
   - img
 - text: Available only on the last message of a completed turn
-- button "Context injection":
+- button "Context injection · @deepseek-ai/dsh-system-prompt":
   - img
   - img
-  - text: Context injection
+  - text: Context injection · @deepseek-ai/dsh-system-prompt
 - button "Think The user wants me to use the ask_user_question tool to ask them a specific question with the given parameters. Let me do exactly that.":
   - img
   - img
@@ -24,7 +24,7 @@
   - img
   - text: Ask question waiting
 - status: Deep diving...
-- text: "Interjection: include the word BANANA in your final reply."
+- text: "Steer Interjection: include the word BANANA in your final reply."
 - button "Copy":
   - img
 - region "Ready to continue?":

apps/web/tests/snapshots/steering/settled.expected.md

@@ -10,10 +10,10 @@
 - button "Branch into a new conversation" [disabled]:
   - img
 - text: Available only on the last message of a completed turn
-- button "Context injection":
+- button "Context injection · @deepseek-ai/dsh-system-prompt":
   - img
   - img
-  - text: Context injection
+  - text: Context injection · @deepseek-ai/dsh-system-prompt
 - button "Think The user wants me to use the ask_user_question tool to ask them a specific question with the given parameters. Let me do exactly that.":
   - img
   - img
@@ -22,7 +22,7 @@
   - img
   - img
   - text: Ask question 1/1 answered
-- text: "Interjection: include the word BANANA in your final reply. {{clock}}"
+- text: "Steer Interjection: include the word BANANA in your final reply. {{clock}}"
 - button "Copy":
   - img
 - button "Branch into a new conversation" [disabled]:

apps/web/tests/snapshots/subagent-conversation/ui.expected.md

@@ -15,10 +15,10 @@
 - button "Branch into a new conversation" [disabled]:
   - img
 - text: Available only on the last message of a completed turn
-- button "Context injection":
+- button "Context injection · @deepseek-ai/dsh-system-prompt":
   - img
   - img
-  - text: Context injection
+  - text: Context injection · @deepseek-ai/dsh-system-prompt
 - button "Think The user is asking for a one-sentence description of event sourcing. This is a straightforward knowledge question that doesn't require any skill loading or tool calls.":
   - img
   - img

apps/web/tests/snapshots/web-search-round/ui.expected.md

@@ -10,10 +10,10 @@
 - button "Branch into a new conversation" [disabled]:
   - img
 - text: Available only on the last message of a completed turn
-- button "Context injection":
+- button "Context injection · @deepseek-ai/dsh-system-prompt":
   - img
   - img
-  - text: Context injection
+  - text: Context injection · @deepseek-ai/dsh-system-prompt
 - button "Search DeepSeek Harness snapshot search":
   - img
   - img