feat(coderd/database): add chat_context_resources table (#26430)

Adds chat_context_resources: a per-chat pinned copy of the agent context
resources a chat is hydrated against. The agent-side table
(workspace_agent_context_resources) is last-writer-wins with no history,
so a chat copies its resources at hydration/refresh to keep a stable view
while the agent drifts.

Schema foundation only (no queries/dbauthz/prepareGeneration/SDK yet).
chat_id FK ON DELETE CASCADE for cleanup parity; no agent FK so the pin
survives agent replacement; PK (chat_id, source); reuses the 000522 enum
types.

coderd/database/dump.sql

@@ -1748,6 +1748,38 @@ COMMENT ON COLUMN boundary_usage_stats.window_start IS 'Start of the time window
 
 COMMENT ON COLUMN boundary_usage_stats.updated_at IS 'Timestamp of the last update to this row.';
 
+CREATE TABLE chat_context_resources (
+    chat_id uuid NOT NULL,
+    source text NOT NULL,
+    body_kind workspace_agent_context_body_kind NOT NULL,
+    body jsonb NOT NULL,
+    content_hash bytea NOT NULL,
+    size_bytes bigint NOT NULL,
+    status workspace_agent_context_resource_status NOT NULL,
+    error text DEFAULT ''::text NOT NULL,
+    source_path text DEFAULT ''::text NOT NULL,
+    created_at timestamp with time zone DEFAULT now() NOT NULL,
+    updated_at timestamp with time zone DEFAULT now() NOT NULL
+);
+
+COMMENT ON TABLE chat_context_resources IS 'Per-chat pinned copy of the agent context resources a chat is hydrated against. Copied from workspace_agent_context_resources at chat hydration and context refresh; survives agent replacement and workspace rebuilds.';
+
+COMMENT ON COLUMN chat_context_resources.source IS 'Resource locator: canonical file path for file-backed kinds, or the MCP server name for mcp_server resources.';
+
+COMMENT ON COLUMN chat_context_resources.body_kind IS 'Discriminator for the body JSON shape. Matches the proto oneof variant: instruction_file, skill, mcp_config, mcp_server. PLUGIN/HOOK/SUBAGENT/COMMAND are reserved for the Claude Code plugin RFC.';
+
+COMMENT ON COLUMN chat_context_resources.body IS 'protojson-encoded variant body matching body_kind. Always populated; non-OK statuses use the variant zero value so the wire kind is still attributable.';
+
+COMMENT ON COLUMN chat_context_resources.content_hash IS 'sha256 over the resource''s original bytes (or transport-encoded server tool list).';
+
+COMMENT ON COLUMN chat_context_resources.size_bytes IS 'Original payload size in bytes; populated regardless of status.';
+
+COMMENT ON COLUMN chat_context_resources.status IS 'Per-resource status. ok carries a populated body; oversize, unreadable, invalid, and excluded carry an empty body plus an error string.';
+
+COMMENT ON COLUMN chat_context_resources.error IS 'Per-resource error or warning string. Populated whenever status is non-ok; may also carry a non-fatal warning when status is ok.';
+
+COMMENT ON COLUMN chat_context_resources.source_path IS 'User-declared scan root that produced this resource. Empty for built-in scan roots.';
+
 CREATE TABLE chat_debug_runs (
     id uuid DEFAULT gen_random_uuid() NOT NULL,
     chat_id uuid NOT NULL,
@@ -4096,6 +4128,9 @@ ALTER TABLE ONLY boundary_sessions
 ALTER TABLE ONLY boundary_usage_stats
     ADD CONSTRAINT boundary_usage_stats_pkey PRIMARY KEY (replica_id);
 
+ALTER TABLE ONLY chat_context_resources
+    ADD CONSTRAINT chat_context_resources_pkey PRIMARY KEY (chat_id, source);
+
 ALTER TABLE ONLY chat_debug_runs
     ADD CONSTRAINT chat_debug_runs_pkey PRIMARY KEY (id);
 
@@ -4906,6 +4941,9 @@ ALTER TABLE ONLY boundary_sessions
 ALTER TABLE ONLY boundary_sessions
     ADD CONSTRAINT boundary_sessions_workspace_agent_id_fkey FOREIGN KEY (workspace_agent_id) REFERENCES workspace_agents(id);
 
+ALTER TABLE ONLY chat_context_resources
+    ADD CONSTRAINT chat_context_resources_chat_id_fkey FOREIGN KEY (chat_id) REFERENCES chats(id) ON DELETE CASCADE;
+
 ALTER TABLE ONLY chat_debug_runs
     ADD CONSTRAINT chat_debug_runs_chat_id_fkey FOREIGN KEY (chat_id) REFERENCES chats(id) ON DELETE CASCADE;
 

coderd/database/foreign_key_constraint.go

@@ -14,6 +14,7 @@ const (
 	ForeignKeyAPIKeysUserIDUUID                                   ForeignKeyConstraint = "api_keys_user_id_uuid_fkey"                                      // ALTER TABLE ONLY api_keys ADD CONSTRAINT api_keys_user_id_uuid_fkey FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE;
 	ForeignKeyBoundarySessionsOwnerID                             ForeignKeyConstraint = "boundary_sessions_owner_id_fkey"                                 // ALTER TABLE ONLY boundary_sessions ADD CONSTRAINT boundary_sessions_owner_id_fkey FOREIGN KEY (owner_id) REFERENCES users(id) ON DELETE SET NULL;
 	ForeignKeyBoundarySessionsWorkspaceAgentID                    ForeignKeyConstraint = "boundary_sessions_workspace_agent_id_fkey"                       // ALTER TABLE ONLY boundary_sessions ADD CONSTRAINT boundary_sessions_workspace_agent_id_fkey FOREIGN KEY (workspace_agent_id) REFERENCES workspace_agents(id);
+	ForeignKeyChatContextResourcesChatID                          ForeignKeyConstraint = "chat_context_resources_chat_id_fkey"                             // ALTER TABLE ONLY chat_context_resources ADD CONSTRAINT chat_context_resources_chat_id_fkey FOREIGN KEY (chat_id) REFERENCES chats(id) ON DELETE CASCADE;
 	ForeignKeyChatDebugRunsChatID                                 ForeignKeyConstraint = "chat_debug_runs_chat_id_fkey"                                    // ALTER TABLE ONLY chat_debug_runs ADD CONSTRAINT chat_debug_runs_chat_id_fkey FOREIGN KEY (chat_id) REFERENCES chats(id) ON DELETE CASCADE;
 	ForeignKeyChatDebugStepsChatID                                ForeignKeyConstraint = "chat_debug_steps_chat_id_fkey"                                   // ALTER TABLE ONLY chat_debug_steps ADD CONSTRAINT chat_debug_steps_chat_id_fkey FOREIGN KEY (chat_id) REFERENCES chats(id) ON DELETE CASCADE;
 	ForeignKeyChatDiffStatusesChatID                              ForeignKeyConstraint = "chat_diff_statuses_chat_id_fkey"                                 // ALTER TABLE ONLY chat_diff_statuses ADD CONSTRAINT chat_diff_statuses_chat_id_fkey FOREIGN KEY (chat_id) REFERENCES chats(id) ON DELETE CASCADE;

coderd/database/migrations/000525_chat_context_resources.down.sql

@@ -0,0 +1,4 @@
+-- The workspace_agent_context_* enum types are owned by migration
+-- 000522 and are still in use by workspace_agent_context_resources, so
+-- they are intentionally left in place here.
+DROP TABLE IF EXISTS chat_context_resources;

coderd/database/migrations/000525_chat_context_resources.up.sql

@@ -0,0 +1,30 @@
+-- Creates chat_context_resources: a per-chat pinned copy of
+-- workspace_agent_context_resources (semantics in COMMENT ON TABLE
+-- below). Migration-specific notes: there is deliberately no FK to
+-- workspace_agents so the pin survives agent replacement and workspace
+-- rebuilds, and the body_kind/status enum types are reused from 000522
+-- and must not be recreated here.
+CREATE TABLE chat_context_resources (
+    chat_id UUID NOT NULL REFERENCES chats(id) ON DELETE CASCADE,
+    source TEXT NOT NULL,
+    body_kind workspace_agent_context_body_kind NOT NULL,
+    body JSONB NOT NULL,
+    content_hash BYTEA NOT NULL,
+    size_bytes BIGINT NOT NULL,
+    status workspace_agent_context_resource_status NOT NULL,
+    error TEXT NOT NULL DEFAULT '',
+    source_path TEXT NOT NULL DEFAULT '',
+    created_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+    updated_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+    PRIMARY KEY (chat_id, source)
+);
+
+COMMENT ON TABLE chat_context_resources IS 'Per-chat pinned copy of the agent context resources a chat is hydrated against. Copied from workspace_agent_context_resources at chat hydration and context refresh; survives agent replacement and workspace rebuilds.';
+COMMENT ON COLUMN chat_context_resources.source IS 'Resource locator: canonical file path for file-backed kinds, or the MCP server name for mcp_server resources.';
+COMMENT ON COLUMN chat_context_resources.body_kind IS 'Discriminator for the body JSON shape. Matches the proto oneof variant: instruction_file, skill, mcp_config, mcp_server. PLUGIN/HOOK/SUBAGENT/COMMAND are reserved for the Claude Code plugin RFC.';
+COMMENT ON COLUMN chat_context_resources.body IS 'protojson-encoded variant body matching body_kind. Always populated; non-OK statuses use the variant zero value so the wire kind is still attributable.';
+COMMENT ON COLUMN chat_context_resources.content_hash IS 'sha256 over the resource''s original bytes (or transport-encoded server tool list).';
+COMMENT ON COLUMN chat_context_resources.size_bytes IS 'Original payload size in bytes; populated regardless of status.';
+COMMENT ON COLUMN chat_context_resources.status IS 'Per-resource status. ok carries a populated body; oversize, unreadable, invalid, and excluded carry an empty body plus an error string.';
+COMMENT ON COLUMN chat_context_resources.error IS 'Per-resource error or warning string. Populated whenever status is non-ok; may also carry a non-fatal warning when status is ok.';
+COMMENT ON COLUMN chat_context_resources.source_path IS 'User-declared scan root that produced this resource. Empty for built-in scan roots.';

coderd/database/migrations/testdata/fixtures/000525_chat_context_resources.up.sql

@@ -0,0 +1,82 @@
+-- Pinned context resources covering each non-reserved body kind plus a
+-- non-OK status. The earlier chat fixtures already insert at least one row
+-- into chats; we attach the resources to the first such chat (ordered
+-- deterministically) so migration tests see a non-empty
+-- chat_context_resources table without hard-coding a specific chat ID.
+INSERT INTO chat_context_resources (
+    chat_id,
+    source,
+    body_kind,
+    body,
+    content_hash,
+    size_bytes,
+    status,
+    error,
+    source_path
+)
+SELECT
+    c.id,
+    v.source,
+    v.body_kind::workspace_agent_context_body_kind,
+    v.body::jsonb,
+    decode(v.content_hash, 'hex'),
+    v.size_bytes,
+    v.status::workspace_agent_context_resource_status,
+    v.error,
+    v.source_path
+FROM (
+    SELECT id FROM chats ORDER BY created_at, id LIMIT 1
+) AS c
+CROSS JOIN (
+    VALUES
+        (
+            '/home/coder/workspace/AGENTS.md',
+            'instruction_file',
+            '{"content":"aGVsbG8="}',
+            '1111111111111111111111111111111111111111111111111111111111111111',
+            5::bigint,
+            'ok',
+            '',
+            ''
+        ),
+        (
+            '/home/coder/workspace/.agents/skills/example/SKILL.md',
+            'skill',
+            '{"meta":"LS0tCm5hbWU6IGV4YW1wbGUKLS0tCmJvZHk=","name":"example","description":"Example skill"}',
+            '2222222222222222222222222222222222222222222222222222222222222222',
+            32::bigint,
+            'ok',
+            '',
+            '/home/coder/workspace'
+        ),
+        (
+            '/home/coder/workspace/.mcp.json',
+            'mcp_config',
+            '{}',
+            '3333333333333333333333333333333333333333333333333333333333333333',
+            128::bigint,
+            'ok',
+            '',
+            ''
+        ),
+        (
+            'mcp:echo',
+            'mcp_server',
+            '{"server_name":"echo","description":"echoes input"}',
+            '4444444444444444444444444444444444444444444444444444444444444444',
+            256::bigint,
+            'ok',
+            '',
+            '/home/coder/workspace/.mcp.json'
+        ),
+        (
+            '/home/coder/workspace/big.md',
+            'instruction_file',
+            '{}',
+            '5555555555555555555555555555555555555555555555555555555555555555',
+            99999::bigint,
+            'oversize',
+            'file exceeds 64KiB per-resource cap',
+            ''
+        )
+) AS v(source, body_kind, body, content_hash, size_bytes, status, error, source_path);

coderd/database/models.go

@@ -4809,6 +4809,29 @@ type Chat struct {
 	ContextError             string                `db:"context_error" json:"context_error"`
 }
 
+// Per-chat pinned copy of the agent context resources a chat is hydrated against. Copied from workspace_agent_context_resources at chat hydration and context refresh; survives agent replacement and workspace rebuilds.
+type ChatContextResource struct {
+	ChatID uuid.UUID `db:"chat_id" json:"chat_id"`
+	// Resource locator: canonical file path for file-backed kinds, or the MCP server name for mcp_server resources.
+	Source string `db:"source" json:"source"`
+	// Discriminator for the body JSON shape. Matches the proto oneof variant: instruction_file, skill, mcp_config, mcp_server. PLUGIN/HOOK/SUBAGENT/COMMAND are reserved for the Claude Code plugin RFC.
+	BodyKind WorkspaceAgentContextBodyKind `db:"body_kind" json:"body_kind"`
+	// protojson-encoded variant body matching body_kind. Always populated; non-OK statuses use the variant zero value so the wire kind is still attributable.
+	Body json.RawMessage `db:"body" json:"body"`
+	// sha256 over the resource's original bytes (or transport-encoded server tool list).
+	ContentHash []byte `db:"content_hash" json:"content_hash"`
+	// Original payload size in bytes; populated regardless of status.
+	SizeBytes int64 `db:"size_bytes" json:"size_bytes"`
+	// Per-resource status. ok carries a populated body; oversize, unreadable, invalid, and excluded carry an empty body plus an error string.
+	Status WorkspaceAgentContextResourceStatus `db:"status" json:"status"`
+	// Per-resource error or warning string. Populated whenever status is non-ok; may also carry a non-fatal warning when status is ok.
+	Error string `db:"error" json:"error"`
+	// User-declared scan root that produced this resource. Empty for built-in scan roots.
+	SourcePath string    `db:"source_path" json:"source_path"`
+	CreatedAt  time.Time `db:"created_at" json:"created_at"`
+	UpdatedAt  time.Time `db:"updated_at" json:"updated_at"`
+}
+
 type ChatDebugRun struct {
 	ID                  uuid.UUID       `db:"id" json:"id"`
 	ChatID              uuid.UUID       `db:"chat_id" json:"chat_id"`

coderd/database/querier.go

@@ -200,8 +200,7 @@ type sqlcQuerier interface {
 	DeleteOldChatFiles(ctx context.Context, arg DeleteOldChatFilesParams) (int64, error)
 	// Deletes chats that have been archived for longer than the given
 	// threshold. Active (non-archived) chats are never deleted.
-	// Related chat_messages, chat_diff_statuses, and
+	// All chat-scoped child tables are removed via ON DELETE CASCADE.
-	// chat_queued_messages are removed via ON DELETE CASCADE.
 	// Parent/root references on child chats are SET NULL.
 	DeleteOldChats(ctx context.Context, arg DeleteOldChatsParams) (int64, error)
 	DeleteOldConnectionLogs(ctx context.Context, arg DeleteOldConnectionLogsParams) (int64, error)

coderd/database/queries.sql.go

@@ -6697,8 +6697,7 @@ type DeleteOldChatsParams struct {
 
 // Deletes chats that have been archived for longer than the given
 // threshold. Active (non-archived) chats are never deleted.
-// Related chat_messages, chat_diff_statuses, and
+// All chat-scoped child tables are removed via ON DELETE CASCADE.
-// chat_queued_messages are removed via ON DELETE CASCADE.
 // Parent/root references on child chats are SET NULL.
 func (q *sqlQuerier) DeleteOldChats(ctx context.Context, arg DeleteOldChatsParams) (int64, error) {
 	result, err := q.db.ExecContext(ctx, deleteOldChats, arg.BeforeTime, arg.LimitCount)

coderd/database/queries/chats.sql

@@ -2551,8 +2551,7 @@ WHERE id = @id::uuid;
 -- name: DeleteOldChats :execrows
 -- Deletes chats that have been archived for longer than the given
 -- threshold. Active (non-archived) chats are never deleted.
--- Related chat_messages, chat_diff_statuses, and
+-- All chat-scoped child tables are removed via ON DELETE CASCADE.
--- chat_queued_messages are removed via ON DELETE CASCADE.
 -- Parent/root references on child chats are SET NULL.
 WITH deletable AS (
     SELECT id

coderd/database/unique_constraint.go

@@ -21,6 +21,7 @@ const (
 	UniqueBoundaryLogsPkey                                    UniqueConstraint = "boundary_logs_pkey"                                              // ALTER TABLE ONLY boundary_logs ADD CONSTRAINT boundary_logs_pkey PRIMARY KEY (id);
 	UniqueBoundarySessionsPkey                                UniqueConstraint = "boundary_sessions_pkey"                                          // ALTER TABLE ONLY boundary_sessions ADD CONSTRAINT boundary_sessions_pkey PRIMARY KEY (id);
 	UniqueBoundaryUsageStatsPkey                              UniqueConstraint = "boundary_usage_stats_pkey"                                       // ALTER TABLE ONLY boundary_usage_stats ADD CONSTRAINT boundary_usage_stats_pkey PRIMARY KEY (replica_id);
+	UniqueChatContextResourcesPkey                            UniqueConstraint = "chat_context_resources_pkey"                                     // ALTER TABLE ONLY chat_context_resources ADD CONSTRAINT chat_context_resources_pkey PRIMARY KEY (chat_id, source);
 	UniqueChatDebugRunsPkey                                   UniqueConstraint = "chat_debug_runs_pkey"                                            // ALTER TABLE ONLY chat_debug_runs ADD CONSTRAINT chat_debug_runs_pkey PRIMARY KEY (id);
 	UniqueChatDebugStepsPkey                                  UniqueConstraint = "chat_debug_steps_pkey"                                           // ALTER TABLE ONLY chat_debug_steps ADD CONSTRAINT chat_debug_steps_pkey PRIMARY KEY (id);
 	UniqueChatDiffStatusesPkey                                UniqueConstraint = "chat_diff_statuses_pkey"                                         // ALTER TABLE ONLY chat_diff_statuses ADD CONSTRAINT chat_diff_statuses_pkey PRIMARY KEY (chat_id);